I can't answer all of your questions, and I am not THE authority on ANY of these points, but here is what i have gathered. And people can feel free to put me in my place if i and wrong on any of these...
1 - I believe that that is what the site needs after expected ad revenue, and the amount is what has been received to date through the Donation Drive.
2 - This is one that I can't answer, and most likely only the Admins (RobA and Arcana (aka Robbie the site owner)) would be able answer with any authority.
3 - The Donor Tag is gifted upon those who have gifted during the current Drive. They are cleared after a drive is finished, right before the next one starts.
4 - This is one where I may be completely off base, but I believe that the adds go by-by after donating. But like I said at the start of this answer, I am not sure.
5 - I believe that is a bit of both. Every click-through puts money in the pot, and Arcana does rent out ad space. I think. He does post info in the CL forum, but I have trouble following it.
6 - I have NO idea who has access to that info. I DO know that there is no way for the CLs to find out without asking the Admins. Not that I have asked, and have no idea if any of the others have, but I have yet to find any mention of who gave what. I think that would be another one of the Admin Duties.