2/At least since 2008 my experience is no HNW/large non-us corporate would be dumb enough to have big US banking exposure (although still use swift). If an HNW sets up a banking relationship it's in (or was in) Switzerland, Singapore, Bahamas etc.
3/In my experience this is non-obvious to US HNWs but slowly I'm seeing more HNWs starting to realise this. Also some more exposed users like TUSD for example have moved banking to Bahamas