About the only way a drive on a USB port would adversely effect the key is a crap USB Hub shared among the two, as a power issue, where one or the other acts like it's disconnecting. And you would know it when you need it, such as a save or loading something. Then you could simply plug it back in. Avoidable.

USB3 is technically probably faster in most use cases than SATA; SATA is becoming a deprecated technology at this point.

Everything MIDI that is setup in Cubase to communicate to VE Pro should communicate, with either in focus, per se.

No, you should hear it regardless.

"solo edit" in Key Editor, meaning the part you are looking at is edited in isolation (with that deselected all parts opened in it are editable).

I described that I had VE Pro '4', (Port 3, channel 2) in the Key Editor, playing notes to that part and even as I was focused on VE Pro '2' I hear it.

But by the same token, if you have a part soloed, it's soloed, your focus "to the front" should not change that.

when you want to hear the sound you have to bring Cubase project to the front; no, you should hear it with any VE Pro 'to the front' or in focus. You should hear it with the VI patch in focus assigning control. Something isn't communicating.

Or by keyswitch ;)

I'm trying to picture what you mean in 2. I suppose you mean monophonic ie., single line MIDI tracks in Logic going to a multimbral instrument in VEP.

Personally on the VEP end I don't find a multitimbral Kontakt, .nkm saves on resources enough to become a mode of operation for me. I do it occasionally when it's a family/from the same library and the reason for that is to compare in the one window the different mic'ing, decca tree, etc ambience setup. EG: Spitfire, Orchestral Tools interface.

Kontakt runs into an incompatibility in VEP when it gets into the 'Unassigned' outputs which are its 32 monos, (default setup 16 pairs but this is now 2 channels in the host, not one) so the functional use of a multi ends at Stereo 10, anyway.

No Vienna Instrument is real multimbral, ie., while an instance may use 4 stereo outs there is a single channel possibility only.

I write almost exclusively in monophonic lines; as to writing chords in a single track, I don't see a problem with, or a necessity of, a multitimbral instrument. If you can assign channel per note you can make a single MIDI track talk to the individual members of a multi independently, or same w. multiple single instances (via the same 'Omni/All' VEP channel matching sequencer assignment).
I write multiple single lines inside one 'Omni/All' track in Cubase frequently, but Cubase has MPE support as well as Note Expression* (*for instance one note in the part may have a different CC1 or CC11 et al curve than another), and full MPE requires "All".

You have to know what CC the knobs send and assign them to the channel in VE Pro.

Once assigned, you don't need to have VE Pro in focus for these to work.

"as you know when you want to hear the sound you have to bring Cubase project to the front, but then when you want set the sliders in VI (adanced tab), you have to bring VE pro to the front and you can't adjust and hear the difference same time,"

No. You should hear the sound with VE Pro in focus. Right now what's in focus here is a different instance, #2, than what I have in Key Editor solo edit, communicating with a channel in #4 and it sounds. Something is wrong if this is not true.

No, the audio, the anything, goes from DAW sequencer to VEP and back, period.

I've had a couple of 13" IME it's definitely too small.

As your needs expand musically your needs for more resources also grow.

for the rather modest sets you mention an i5 will do you but the lack of screen space is more than it looks like on paper. With the new Macs, you don't have the option to expand it yourself. I think 16GB would therefore be a mistake.

Any of this is a substantial investment to my view, I would recommend as much a future-proof system as you can afford. I got the i9 with 32GB and a 1TB drive. I almost regret not getting it with 2TB but the price diff is huge.

Latency isn't so much the issue, it's compensated for, but if you do very much of this the round-trip of it all tends to be more taxing than the primary use of VE Pro. If all you have in the project is audio it's not that bad, if you're doing MIDI to instruments host in VEP you can run into management of resources.

You can group channels, you can have a bus for parallel compression and send to it, you can establish a compression bus and place the channels you want effected in that bus...

If you want to do as a DAW group does, do the latter but eg., the bus the group all resides in is just for a group send and send to the compression bus as a group if you want varying levels, ie., send behavior. There is really no reason to route it to and then from the DAW just for that. 

Me, I had reasons. First, organization; 1) the automation parameters in the VEP 6 paradigm for the instance essentially considered an external rack, were relatively few and appeared right at the top rather than where they will have in my ad hoc addition of things somewhere harder to locate.

This is more or less obviated now in VEP 7 as the names for things appears in Cubendo instead of the parameter number, so I feel freer to put them in the order of appearance left to right. 

2) the send levels then for a send to the instance were the objective '-inf' to the chosen Cubendo max, for me it appears as 6.02 (dB); vs for VEP 6 sends inside an instance, "0dB" was displaying as somewhere between .7 and .71 (ie., type .706 for 0dB) & everything relating to 0 to 1; and It was that different a look for me.

This too is obviated by VEP 7 where most of it is now the objective values, it's the exact same look (except for a chinese-looking graphic for -inf now)

and iirc copying a range of values from one to the other was not right.

I should note that if you're going to do this, to print the result at all means this is an external instrument or effect to the host and it means Export in Realtime or you have nothing but an empty file, or if it's just a two-file that information is missing.

You can route it thru your DAW sequencer, set up a send from a VEP instrument channel to FX = Vienna Ensemble Pro Audio Input and send it. Doubtful this is a significantly better use of CPU if not the opposite but for certain things like an amp room I do this way. 

I think optimal use of cores, if that's the goal a single instance is the better use case.

If by  'load [] into midi 1 there is no problem but if I load the same or different into midi 2' you mean the indication in VEP of channel, there is the channel assignment in the instrument. To the left, where it's the same as any multitimbral plugin. So a multi would be VEP channel All with the individual parts assigned 1-16. But ensure the assignment is also done in UVI Workstation.

Cubase 10.0.20, VEP 7 build 834.

If you're on Windows, the different behavior may well be explained by the OS difference.

 I just quit the vesp I've been working on for a while now and it quit relatively promptly this time, a couple of times actually. Causing the system to freeze was pretty scary but that's only the once.

OSX Mojave has a leaky Spotlight Indexing which I have now disabled.

Kontakt 5.8.1, Kontakt 6.0.4, 6.1, 6.1.1 and probably all current-day Kontakt, period.

Since build 834, the values in Status Line or in Project Browser are not even accessible, stuck.
Values written before this build automate the instrument, but writing new values is impossible.
Values created by a tool in the lane for the parameter in the project window are fine but this is the only possible way to write automation currently (unless live, which I have no, or even know of any way to do for these lanes).

So the values are necessarily coarse as well as unknowable. 

Mr Saletag informs me this is from the VST version; (I had to reconnect but) I can confirm the AU version works normally. Avoid the VST on Mac for now, I'd say.

That's pretty weird. Are these two parts clearly panned differently?
It strikes me as an aural illusion. I write monophonic parts almost always, linear and contrapuntally and there is no such behavior ever or anything like it. But I pan using a power panner rather than MIDI pan, which is problematic because all the does is turn the volume down on the other side in reality. Still, that makes no sense objectively.

I have things in a collection some of which read as "Full" some of which don't (never bought the Standard of it separately), and some of the download instruments, same thing; three or more of which have only the one version.

But yeah, if you never bought singles yoiu wouldn't tend to see 'Download', and none of my files look like that anyway.

If you're looking at the MIDI tab in Automation Map, all you have to do is make sure the [Port and] Channel from the DAW are assigned and match and your controller is one of the inputs to the MIDI track. 
This assignment is per Port and Channel (or if you aren't using multiport via VST3) simply the channel.

If what you want to do is assign the CC to more than one parameter in one go, no, you'll have to do it individually, I don't see how possibly there would be a magical link function, if I'm reading that right. You can manually assign the CC again and again to different parameters in the same channel.

Is 'Activate Window by MIDI Activity Focus' is ticked On in Preferences?

It's not exactly as simple as has been presented, except if all you did was Cube Standard and then added Extended, probably in VSL Data you may see Full vs something else, and the not-Full will be redundant.

I have I think 3 Download instruments which have no distinction, there is the one version and it's quite 'Full'.

I wanted to use QC finally with a little NanoKontrol2 I bought last year. For MIDI, I have no real need to control faders in the mixer by such a thing. It never happened (known issue and Korg has done nothing for years, Cubase on Mac is a non-starter, and problematic on Mac pretty widely for the last several OSes). 

It's rather outdated, Quick Controls. The whole paradigm of changing pages... a number of things still do that, it's too fiddly for me any way you cut it.  What controller are you using?

I haven't followed this all that closely but I have seen it a few times here on the forum with no official response.
In my assessment it is possibly something which can't work. Which is where Kontakt divvies the outputs to its Unassigned paradigm after a point. I'm pretty sure it can't work in certain ways as it does in a DAW host.
When you assign outputs in eg., Cubase or Nuendo, no matter what you set as a configuration, the outputs displayed in the dialog are the default; in VE Pro the display is objective, just the numbers. Which breaks down where there is this distinction (where Kontakt is dealing in mono pairs instead of single stereo), so I don't think the feature sets agree.

Fortunately I don't use extensive outputs from Kontakt for years now. This was a bit crazy-making to test.

It loads faster than 6 here, easily.

I don't mind force quitting, but right now it hung loading a different .vesp and force quit out of that; and while it appears to not be running, the icon is in the dock and it will not start. I will have to reboot the machine.