In my experience the AI will continue to build settlers and found cities even during wartime. Are you considering capturing settlers? Yes, especially once the horses are hooked up. Would hope he behaves just as you predict -- that's an extra worker(s), and, if he is building settlers, then he is not threatening us and we can continue to develop efficiently.
Uranium must be either abundant or placed in the starting location (or both) otherwise the game is impossible to win. I don't expect problems there. You are probably right (and if not?), but if it is abundant, then there is some potential gain here as well.
Worker stealing would be a way to keep Gandhi backward. The question is if this is good or bad? Do we want him as a trading partner until Fission/Rocketry or do we want to keep him weak until we can attack?