How are you doing the upgrade? Just buying a 9-speed wheel and throwing it in?

1. Should work fine, as long as the RD has enough travel, and isn't worn out/sloppy. Downtubes will shift friction, or you could find some 9-2peed downtube levers.

2. It's possible that it might drop in with no problem, or with a slight bit of finessing(spread the dropout a bit by hand). Can only find out by trying it. Worst comes to worst you can always have the frame coldset.