Honestly, right now, the AI need to have their awareness fixed. It'd be great if they actually raced each other and tried to overtake, rather than just following each other around.
Depends what you mean by getting the physics right.
You can't expect the cars to handle as they would in a racing simulator, that would be a waste of resources. Personally i felt GTA IV's physics were the best of the series.
The time period of this game seems like it'll be around the time of the "Les Enfants Terribles" cloning process of Big Boss, which leads to the creation of Liquid Snake, Solid Snake and Solidus Snake. This is what led Big Boss to leave FOX