Go with Facebook CPC or Google. It will be lot easier if you can get the coupon and i can give you method if you will
Is your affiliate program related to what you sell / promote on your site? I have an affiliate program, but I don't promote it per se. I promote my site and benefits of using it, and then, if people see a value in it, they sign up for the affiliate program. I use: 1. PPC (AdWords / Bing) 2. Twitter (can't recommend it enough)
No, not in my case. I just keep growing my twitter account. I have close to 27k followers. You can email every new follower a welcome message offering them to join your aff. program. I never offer anything via emails myself, but quite a few people send me their offers when I start following their accounts. You can use http://tweepi.com/ to grow your twitter account.
If you are new in affiliate marketing Facebook destroy your money. So learn first before start advertise.