4mybaby - It's really up to you, but in my opinion, if you want to use them all, you should have them all tested. You might want to do just some of them at first and use the ones that you've tested, and then send in a few more. Like if you just chose half of them or something, 200 prints is still a lot of choices.
Kunkle - I am not aware of any minimums, none were mentioned to me at any point. But you might want to ask if you email or call him :)