Donations will never work as long as the game is still an FPS. I know Blacklight Retribution lets it's players rent weaponry, but donating guns to friends just seems plain pointless, especially with how easy it is to rack up coins.
Status effects are a maybe, definite for the flamethrower, but that's about it. There's nothing else that could really give a "health bleed" effect in the game besides the wand (or all rifles/pistols if you want it realistic).
You can equip armor in the game, however it is short lived indeed. I agree with a permanent stature of armor for players.
Report button has tons of ways it could go horribly wrong, especially if that 9 year old decides to report you for "hacking" or just in a fit of rage because they can't handle you.
I fully agree with PMs. This could be so much more helpful, especially if they added a team chat, would allow for strategizing.
Vehicular combat would involve extreme lag, given that Unity isn't exactly the engine to handle massive setups like this. Even so, with all the device limitations, you would need to make it something that doesn't involve too much lag (for example, no weaponry to reduce explosion effects).
A kick button for the server host will never work. Once players start joining and lighting it up, the host 90% of the time leaves after 5-10 mins of starting the server. Perhaps a more generalized vote-kick or ability to appoint members as temporary hosts would be better for this.