I suggest that you avoid Beaver valves. My cylinder valves failed their 2.5 year test in the summer, I was stunned at the time. Fortunately my LDS has an excellent approach to customer service.
You should also consider what wing/harness/backplate arrangement you feel comfy with.
Twinsets are quite heavy, buy a decent trolley.
Regs are regs, if you are happy with what you have, use them.
Don't know if you use nitrox, but if you are diving in the 30-40m range then consider using nitrox
I like to have a gauge for each cylinder. In my case I have a standard pressure gauge, the other is my gas integrated computer (Suunto Vytec)
Some people really struggle to start off with getting their trim right. So start of in the swimming pool or max of 6m.