Sorry I didn't reply sooner (our local ISP service has been pretty doggie the last few days)
Cartridge alignment: Instead of wasting your time with my feeble knowledge, check out this artical. It covers most of the basics, though you can find (much) less expensive guides that are just as good (the guide that used to come with shure carts is considered one of the best).
http://www.audiophilia.com/features/cartridge_setup.htm
Tracking force: redshifter made an excelent point. Put another away, "a little two much is better than not enough". And you will also find that on some records, you may want to turn up or down the tracking force from your "zero" setting.
Dual tables: I'll yeild to WAB as I have heard several, but only owned one and it is set up for 78's.
Needles: If you buy ANY used cart, plan on replacing the needle. The are several places, but this one will have one for just about everything:
http://www.garage-a-records.com/cart.html
Cart mounts: There are two basic types that are "standards" - H mounts and P mounts. The H types bolt to the headshell from the top. P mounts plug into the arm itself and have a set screw. I'd recommend going H (which most of the tables recommended so far will use), if for no other reason, you will be dealing with them more often if you get hooked on vinyl. (it happens)
Tone arms: on high-end stuff go with a straight arm. On low end stuff it won't make as much of a difference as a getting a good table.
Other thoughs:
The most important thing is having good, clean vinyl. It all starts there and the best table in the world will sound just as bad (and probably worse) with trashed vinyl.
1. Always brush an album BEFORE and AFTER play.
2. Always put it back in the jacket WITH A SLEEVE when done.
3. Always stand them up for storage, and hopefully in a tight group.
4. Never play an album more than twice without letting it rest (this is why a lot of albums are warn-out)
I can't recommend a $200+ record cleaning machine, but I can strongly recommend a $20 discwasher, Pickaring, or Philips carbon fiber brush, and a $70 disk doctor cleaning kit (use once per record)
http://www.discdoc.com/
Well thats enough for one post
