Some feedback:
* [Edit: Looks like it's right there in the center and I'm just blind. :)] I couldn't find the pricing after the 10 day trial anywhere. This frustrated me and made me not want to try it at all without knowing what I was getting into.
* Twitter frowns upon auto-follow/unfollow services. You should be very careful with this. I recently had to make changes to my own service because the Twitter API policy team didn't like me telling people who unfollowed them.
Great work, I look forward to the second part!