Yes, it seems nobody found anything wrong in it in a recent topic.
See above.
Yes, this is what the manual says.
This topic fits the new category on the forums, which is not created yet (and you don’t have high enough Trust Level yet). However, note that you can in theory use Qubes for those things, too if you do GPU passthrough.
Update: The new category is created: https://forum.qubes-os.org/c/all-around-qubes/25.