Don't invest your time in learning the current stable version (2.49) UI quirks.  By the time you manage to master it, 2.6 will be out lol.

Download, for instance, this build of 2.5. It's already production ready for the most part. Obj export/import between Poser is reported to work like a charm (can't check it myself right now).

Go to BlenderCookie. There is a lot of great tutorials there. Start with introduction.