2) Can't answer that, as I've done DivX only a smattering of times with different programs. VirtualDub and the right codec should be able to do it.
3) What do I set the resolution as to rip in 4:3?
4) What do I set the resolution as to rip in 16:9?
In DVDShrink (and DVD Decrypter), you locate the 16x9 stream, and/or 4x3 stream, and rip the appropriate one. If there's 4only a 4x3 stream to rip and you want it to be anamorphic, you will have to resize it in something like VirtualDub, and re-encode the MPEG.