Easy ones first:
1.) Does the MP reverb work? If yes, ignore the startup error. SVP is trying to set it up like software in the menu because it "sees' the card as a VST plugin.
This is one of those things that get taken care of in updates. Too bad there aren't any.
2.) 4.5 was mostly a bugfix but nobody remembers what those fixes were. As far as anyone can tell, either 4.2 or 4.5 should run just fine EXCEPT 4.5 has a bug in the Notation window that causes it to display improperly and crash if you try to edit in it. That's right, the bugfix had another bug. There is a work-around but unless you work heavily in notation, it's not worth worrying about.
Now:
Strip Silence is indeed an offline operation unrelated to the ASIO. It's just an after-the-fact noise gate. How much memory do you have allocated to SVP? Oddly, you can sometimes have too much - yes that makes no sense, but it's true Try a few different settings in the Get Info window between half to twice the shown recommended amount.
My only question is: when you say "After a few short audio recording operations, when I go to Strip Silence a stereo audio event, the system immediately hangs."
Exactly what do you mean by that? A few rec operations on the same track, on different tracks? If you're set in rec prefs to place each recording in a different file, but laying them end-to-end on the same track, then trying to strip silence from the whole trackā¦ who knows, your computer could explode for all I know. Try stripping after just one recording and see if it hangs. Holler back.