One thing I've learned in my days of muzzle loading is I much much prefer a stainless steel muzzle loader. I don't think I'd buy another one that was blued unless I got a smoking deal. The stainless is just soo much more forgiving when it comes to cleaning and easier to clean too. The blued ones rust way too easily if you don't clean it right away imo.
I also prefer 209 primers over #11 caps, but most muzzle loaders now use 209 primers.
As for bullets, I don't like the Powerbelts all that much. I've tried them and they are great in everything I've tried them in when it comes to accuracy. Infact, I couldn't believe how well they shoot in some of the guns I've shot them in. That being said, when I tried to deer hunt with them, I found that I wasn't getting a blood trail at all, but I'd usually find the deer 30 yards or so away. After losing a deer that I know I hit as it fell over and started flapping then jumped up and took off, and I only found a few specs of blood on a tree it had rubbed up against, I finally decided to switch. I've been testing some Fusion bullets, and they seem to expand great in dirt, and perform great. I got to try them out on deer this year, as well as have a friend shoot a deer with one. I've been super impressed with these bullets although they are fairly expensive. Another good choice is the Speer Deep Curls which in my testing seem to perform similar to the Fusions, only I've never tested them on a deer. There are also several other great bullet choices that I've never had any experience with.
So, I'd try something else in addition to the Powerbelts. If you use the Powerbelts, I think the key is to use them with a light charge as they don't seem to like the 100 grains I was pushing them with. They are very accurate though as I said.
As for powder, it's all a personal preference too. A lot of guys like BH209 and I'd like to try it, but haven't yet. Some guys like pellets, and some like loose powder. I'm sure I will get bashed for this, but I like pellets. If I was shooting at the range 100% of the time, I'd use loose powder as it's a lot cheaper as you get about twice the amount for the same price. However, when hunting and out in the field, I've found messing around with loose powder to be more of a hassle than just popping in 2 pellets. Hunting situations is where I see a big advantage to the pellets and since I mostly hunt with my muzzle loaders, I use pellets. This is just a personal preference though as I know quite a few guys who use loose powder out in the field. I've also found my gun prefers Pyrodex over T7 pellets, but that's just my gun and since it's cheaper and shot better I stuck with it. You really need to test different types in your gun and stick with what it likes as every gun likes something different. This is the same with bullets. If one doesn't shoot accurately for you, try another.
As far as primers, it's all a personal preference too. Winchester W209 primers are pretty good as are the T7 primers. I've also had great luck with the Fusion primers, but at the same time I've seen no difference in the field between them and W209's so who knows if it's worth the extra cost.
Also make sure you clean your gun after shooting it as they will rust quickly if you don't. Be careful as muzzle loading is an addictive hobby and the more you get into it the more I expect you will experiment with different bullets and powder.