Is there a guide to the companions for New Vegas? Like where they are located and what's required to get them to follow you?

Try this maybe:

http://fallout.wikia.com/wiki/Fallout:_New_Vegas_companions

It's not complete yet, but it's being edited constantly.

i know about Boone and the Trading post gal....

Boone is in Novac. you have to do the quest where you find out what's happened to his wife... ask him to hunt Legion and he'll join with his sniper rifle and you get a 1st NCR Recon beret... the same one Boone wears..

im not sure about the Trading post gal but all i did was talk her into joining me, no mission at all... but her punches are insane... i was being attacked outside of New vegas and she literally punched the dude's head off lmao...

im not sure about the others...

Thanks!

It's a damn shame you cannot recruit Sunny Smiles. She's pretty bad ass