Creatine helps muscles use stored energy (supposedly)
Not supposedly, definitely (at least according to we currently know about the muscles). Your muscles use creatine naturally in its energy processes - remember, creatine in certain amounts is produced naturally in the body.
Protein is the building block of your body, as well as the least utilized of the energy-producing nutrients. When you build muscle, your body is using the actual protein and turning it into muscle. You can't build muscle without protein.
Apples and oranges. One is fundamentally necessary to building muscle (protein) and the other helps you workout better by giving you better energy utilization (creatine).
If you are looking at creatine (and I say this every time to everybody since it's not that widely known at the moment) look into a buffered creatine monohydrate like Kre-Alkalyn. Normal creatine turns into creatinine fairly quickly (with contact to moisture in air, in a mix, or in the stomach) and so it's only 20% - 30% absorbed by the body. When it's buffered (i.e., surrounded by a buffering agent like calcium) it can reach the muscle undamaged and bring absoprtion up to 95%.
Also, since it's not turning into creatinine in your stomach, you won't suffer from the stomach aches and dehydration sometimes associated with creatine use.