1: Yes and no. Yes, you need more than 1 ACCOUNT so you sorta have to buy the boxes for a new cdkey to make a new acct(and get a free month with the original wow cdkey) or send yourself a Recruit-a-Friend invite/trial account(but no free month on the main account without a box upgrade); no, you can run off a single, lone installation of the WoW program, I do :p

2: Yeah you can do it manually or with Maximizer, Maximizer's a little more efficient about it

3: Yeah, though I think Synergy can send keys as well, but I don't know for sure. There's alot of options, Synergy should be enough I'd asusme, but again I only have experience with AHK and keyclone :p

Welcome and good luck ;)