It's in here the answers to your questions, they just hasn't released it yet.
https://www.bungie.net/en/News/Article/46611
English
-
Power Ammo respawn timers for all Quickplay modes have been reduced ~30%. Power Ammo respawn timers in Survival have been reduced ~40%. Power Ammo respawn timers in Countdown have been reduced ~25%. Ammo counts have been adjusted in relation to these timers, and in relation to weapon type. Nothing about more than one player being able to get power ammo from the kiosk
-
When players with power ammo are killed, they will drop bricks like D1 Y1
-
Well either way thought it might help, I don't play pvp, hell I don't even play this game anymore it's terrible