Traps, here is a quick and dirty link I dug up..
http://www.algone.com/cycle.htm
that has a diagram of the nitrogen cycle in a fish tank, which is basically what we are talking about here.
I would like to reccomend that you purchase a product like CYCLE, or another beneficial bacteria product, just go ask your pet store guy for one, and he'll gladly sell it to you. what your doing is buying a culture of good bacteria that will speed up the cycling process in your tank, they will colonize on every surface or rocks, plants, the tank walls, in the weave of your filters, on the silicone, EVERYWHERE (this eventually happens in every tank, your just helping speed along the process.)
I think this is great stuff, and it will probably keep your fish from going through unessecary stress. (but you still need to do everything biggun said!
here is another great article on NEW TANK SYNDROME.
http://www.bestfish.com/breakin.html
remember, were not 'getting huffy' we are trying to mentor you in a new hobby and help you learn so your successful. We want you to have fun and enjoy this, and all to often newcomers to the aquarium hobby fail because they are not armed with the right information.
10 gallon is fine for now, and as said, as the fish grows, so does his home, just like a family.
Also, you will want to get him on the pellet food as soon as possible, one reason many people fail with the predators is the live prey the feed, feeders are usually stocked heavily and disease can be a problem, if your devil eats something he can't handle, he'll get sick to.
One way to train him off live and on to frozen is to make a feeding stick, find a tube that is clear and attatch a paper clip to it, silicone works best. You use the paper clip to hold a dead fish, or a piece of chicken, or something else he might find tasty, and you wiggle it around, get him to strike it. It should be loosely attatched so he can pull it off and swallow it. over time, you move it less and less, and then start throwing the food in without the stick, or try waving pellets on the stick eventually, the idea is to introduce a common demoniator, the stick, into the feeding process, so he associates the stick with food, not the food.. I know it's weird, and maybe a little hard to understand, but it works on a number of species, I don't know if it will work on a red devil, I am betting his appetite and attitude will let you brake him of the live food habbit strictly by starving him.