Unless you're having issues with marker performance as is, leave it stock and spend your money on paint. My basic upgrade process is this:
1. Accuracy/consistency issues --> Barrel/regulator
2. Chopping --> Bolt
3. Poor Efficiency --> Bolt/tuning/valves (if applicable)
Anything else for the marker is probably a waste of money. For hoppers, I get a speedfeed and that's it. GA/Ninja regs are nice but honestly I've never had a problem with a stock regulator, even on a ****ty aluminum tank. As for the mask, any quality product paired with the appropriate lens will serve you well.