I think that the reason for the PC version having more options is that every PC is different spec-wise. The need to change certain options for better performance is needed. For the 360, since every console is the same and the system is well more than capable of running this game, there is no need to change any option you mentioned.

However, yes, it does slow down a lot when loading zones and during certain events like Campaign and Besieged. In which case, this is a design problem. I'm sure that it might alleviate the problem some if the number of models that displayed could be reduced, but I doubt that it's the system (spec-wise) itself causing it.

I think that the disc is only needed because it's to prevent people from getting the game for free in a sense from other players. It's there just to prove that you have the game and it's an unnecessary catalyst needed to boot the game. So I agree with the Games on Demand option, because even PSU is now available on it and it was the same as XI: it needed the disc to be present even though the whole game was installed in order to be playable.