If your 'Displays of your banner' stat is higher than 0 you've been activated.
Every exchange is low.
After that 1000 is gone, you then get 2 credits for every one banner shown on your own site. Yep, you can align it however you want, just make sure the link, and image codes aren't changed. It's a cache buster. So people's web browsers don't assume it's the same image every page. This is just to make sure you get credits for each and every button shown on your site.