Oh you have no idea what you're getting into. When that one main character did that thing that caused all that other crap to happen, WOW. Seriously, WOW.
I've never played a better game on the system you're talking about than this game.
I think so. While Treyarch were considered jokes when World at War came out, Infinity Ward really screwed the pooch when they came out with Modern Warfare 2.1... errrr I mean 3. From all the interviews I've seen with the people behind Black Ops 2, they seem to be actually listening to players' complaints about dedicated servers, single player campaigns, graphics, etc. I'm not pre-ordering, and definitely won't spend $60 on it, but I'll still be paying attention.
Honestly though, the most fun thing of any of the CoD games recently has been the zombies mode. Thankfully that's been included in Black Ops 2 as well.