No, 4.2 is still supported, and whonix-17 is going to be supported as long as 4.2:
Just don’t postpone it too much or else you risk ending up with issues and no time to fix them.
Happens all the time:
I haven’t encountered any bugs either, and IMO 4.3 is a bit faster. I haven’t used 4.3 for a couple of weeks at this point though, maybe all new freeze-related posts are due to a buggy update or something.