Most pet store care sheets stink. It's more like a maintenance way, rather than the best way. Don't worry about feeding him in his cage, they won't associate you with food unless you have really been rolling in rat feces. I feed all 8 of min in their tubs, and have never had a problem. They have a really good sense of smell, and can tell the difference between you and a meal.

Most people recommend feeding in their cages. They shouldn't be handled 48 hrs after eating. It takes that long to digest their prey, and are really easy to stress out with a full belly.