WELCOME!!!
This situation sounds pretty familiar. I got my first snake my second year of college without my parents permission. They were not pleased. Too bad!
Since I didn't live at home and living off my own money, it really wasn't an issue. I did bring her back with me once for winter vacation, but from then on I just had a friend check on them when I was gone.
My parents still don't really approve of my hobby, but they have accepted it for what it is.
As for keeping rats and snakes, its totally cool. A lot of us keep our live feeder rats in the same room as the snakes (I know I do) and there are no issues. Just do a hand wash when you go from handling the rat to the snake to prevent a bite.