Yes. I know, that Steinberg had a few discussions with Microsoft and weren’t able to convince them.
One solution is for the major DAW vendors to all include the universal runtime in their installers. I’m preparing a mail-out to the major DAW developers, to ask them to include this. This way, plug-ins without installers would still work (granted it would mean that the customer has a newish version of the DAW installed).
It depends. 64 is the worst case. Since VS2017 the static runtime takes up two FLS slots. So if the user loads 64 statically linked different plug-ins created with VS2017 - then loading will fail. If you open the same plug-in twice then this only counts once as it only needs to load the dll once.