Mags are fine just no fake bullets (ie G36 and P90 mags).
Rails should be fine (they're just pieces of metal after all....)
You should go out to a game one day see what it's like, and the Kraken is more than gameable. In fact after a few reliability upgrades (shims, etc.) it should perform to a good enough standard to make your first game fun.
I only spent about $600 for my stuff from the classifieds so I would suggest that if you want something else (once the bug hits you and you need more to expand your armoury) or even some extra parts/gear to get verified and buy from there.
ಠ_ಠLess QQ more Pew Pew
READY TO >> RACE