tank armor buff

maybe its possible to add a buff for tanks (non paranoia) that works as melee armor?
like the old mutated tanks at coop?
and sure it shouldnt work for the whole life u play as tank, maybe for 30 sec and make it slowly reload. with 1 min cooldown.

and some other questions :
decreases the negiator buff the bounty cost for infected too?
and when u pick up a x2/x5 toaster or u got the double exp pack it this also shared with the charity skill? or just the basic exp?