Not sure about the 100 rd hopper, I've seen the tac cap (got one). As for the regulator I don't think it would do much, A5's are gas hogs, best I've done is upgrade for better air efficiency, they have lots for that but it will never do as well as electric markers on air. Probably what saved me the most air was getting a new cylinder that has the blow back valve on it, and upgrade the barrel to fitted fins.
Of course I've never tried an actual regulator on mine so who knows it might do great, let me know.
Here are some good upgrades.
Cyclone Feed Squishy Paddles
TechT Lightening Rod
TechT Quick Exhaust Piston Housing - Black
TechT Vortex Mod
Zero Kick Hammmer