In the good old days, a lot of parents pushed their sons into the military to get these kinks orked out. But, that is sooo not a good idea these days......... I agree, seperate stamps, seperate shopping, seperate meals, take care of yourself. . .
so far you're dynamic is called "enabling". Enabling him to stay immature. It isn't helpful in the long run. Change is tricky, try to find a way to have a sense of humor about it....
Good luck.