1. I've only had experience with the older one from AI and it hasn't given me many problems. I've heard plastic ones are better for your fill valve. I've recently read something about one adapter pushing the valve/oring on the propane tank too low and getting stuck on open. Perhaps someone could elaborate.
2. I've only had experience with KJ mags so I can't help you there. Sorry
3. You will also need light wt. silicon oil and a heavier wt. oil for lubing your gun. A few drops of the light wt. oil into the propane tank valve every few fills. Some people say 1 drop per fill. There are also gas adapters that have an oil reservoir. The light wt. oil can also be used to lube the o-rings/seals although they should be properly lubed if you do the few drops per fill. The heavier wt oil is to lube all other moving parts. You'll also need bb's and things to shoot at
That's what comes to mind. Hope it helps!