Floor pan rust

Those aren't too bad, and if you can weld them up without blowing a bigger hole in the floor, that would be a good way to go. As far as rust-proof paint, lots of people have great luck with POR-15 paint. Yopu can spray it or brush it on and you can get it through lots of places, like Eastwoods Tools.

Depends on the sizes of the holes and the integrity of the surrounding metal. If they're just pinholes and you've got solid metal just filling them is ok, slightly larger holes you might want to weld a patch over.
After my repairs I wire brush the area real well and then coated it with POR-15, it binds to rust and seals the metal from moisture and air preventing future rust problems, but follow their directions carefully.
For more info, you may want to check Oboebrian's FAQ sticky in Tech, and/or do a forum search in Tech for floorpans. Good Luck and keep us posted.

Here's the thread with my floor rust repairs:
http://forums.stangnet.com/showthread.php?t=724205

-Chelle