Yes the M134 minigun "manpack" version is included with the bunker pack 5. Someone needs to fix the anim of the non firing hand though IMHO. This thing is cool to relive moments from predator and such but is so unrealistic it is not even funny: in the real world, no one would be able to withstand the massive recoil energy this thing creates.
As far as a knock out dart gun, It would be "possible". If the rounds were configured to only do a tiny amount of damage (like that paintball gun addon), you could use an eventhandler assigned to all units with a trigger using thislist.
Whenever someone is shot, the EH would check if _ammo == "dart", and would trigger a command to "knock out" the victim. You could do this several ways. What comes to mind would be to setbehavior "careless", and playmove "combattolying", "lyingtotreatdlying" although you would have to expeiment to make it look good and be sure it worked. After a semirandom time elapses the unit would "wake up".
Oh, and to make the Arnie/minigun thing complete, LiquidSnake has a new facepack with Arnie's visage (even if the models are a bit too skinny).
-Grendel