1) They are already Mitigating.
2) No shit....
5) That's most likely because they use DDoS as a scapegoat to buy more time to fix the real issues, which is this broken patootie game with terrible networking. You have a decently valid point there because if it were DDoS a restart wouldn't do a damn thing. (Atleast one would hope this is the case, because any idiot in this community will blame DDoS. A tiny lagspike happens and it's all you see in chat.)
6) Their server is hosted on a physical box, located at Softlayer Technologies, not their office. Google it.
7) Why not just fix the in-game issues instead? Maybe the game is causing the issues on the server and the server is perfectly fine.
8 ) Well GTA for example is Peer2Peer for the most part, while it calls from R*'s server for things like money and others that were once abused and now patched.
9) Yes, bingo.
11) If the ISP was NULL'ing them you'd know...Because that is what they'd be doing.
14) You want to be the one to transfer all of that Data, and pray it doesn't corrupt along the way? Also, what the fuck man.