Hi!
You can add weapons/ammo to vehicles by the addweaponcargo/addmagazinecargo commands, e.g. chopper1 addmagazinecargo ["ZuniLauncher38",10] would add 10 FFAR Rockets used by the Cobra and UH60 to the ammo chopper...
I dont think you can make the chopper able to heal... ...unless you change the config.cpp for it... ...or download a chopper with healing capabilities (there's one in the NamPack 2)...
cheers...