1) I have regs that are designed for cold water. I will have to figure out what a Y valve is.
2) I already have 2 120s. Are you saying have 2 more?
3) That was something I was contemplating, getting a backplate and wing.
Sound advice from everyone.
Best advise anyone can give you is this: go get a couple hundred more dives under your belt in the next 2 years, then find a good instructor. Let him/her walk you through buying solid gear for the type of diving you want to do. Then get the proper training to do this safely...preferably take the classes with a regular buddy that wants to do the same dives that you do.