Feeding them isn't an exact science. Do whatever works. Little guys can eat every 5 days so it wouldn't be bad to feed him again on the regular schedule, but if you want to wait a full week that's fine too.
I'm not an expert, but I'm pretty sure a 4-degree temp difference isn't a problem. At least, I don't worry about it with my snakes and they're doing just fine. As long as it doesn't get hot enough to burn.
Oh, if you want to switch him to f/t, it's best to do it before he gets too attached to live. You do have to be willing to let him get a bit hungry though (but when they're small don't make them go too long if they keep refusing). Heat the rodent up nice and warm, especially around the head (hair dryer works well), and dance it around with tongs. . .if you do it right the snake never knows it's not alive. If he strikes, tug on it a little so he thinks it's struggling.