The eCPM is about 0.03 - 0.1. They accept all of your traffic. If you put 4 banners on your site, all page impression are 4 multiply with impression of each banner. And the last one, they don't have pop-up.
Congrats on your payment I have an account with them, but never actually used them. When you say 4 banners - do you mean 4 same HTML code (one placement) or 4 new banner placements?