Great guide.
It really says alot about a game when you have to exploit it's user interface to get achievements that are completely unreasonable.
As for the long achievements, here is way that is a bit easier if you have 4 controllers (or even the big button controllers from Scene It!)
Go to start game, press 'Start' on another controller. Use the other 3 controllers to sign in as "Guest", which would look like "K4N4GE(1), K4N4GE(2),...etc".
Then go to quick match and hope there is no lobby in progress, then hit the 'x' button and now you have an entire room filled with your gamertag. No way of anyone else joining and giving negative feedback for non responsiveness. The Scene it controllers don't seem to run out of batteries as long as you are actually not pressing anything, and if your first controller is wired, it won't time out either.
Pretty much the same method as K4RN4GE posted, but since fewer modems are needed, there is a less likely chance of the game lagging out or anything, and also makes it so random gamers don't accidently join your session.