A very popular trick to getting far in the waves was opening the two stairs. This allows you to still access the random chest, and manage your area much easier. There's three windows (including the wall) in the supplies room, and the stair case. Once you get good guns, just camp in there and have one person watch all the windows, and one camp at the stairs with MG/FG/Flamethrower/Ray Gun/Browning.
As for perk-a-cola, I've heard roomers that there's a new perk or something that lets you revive teammates faster. Along with that, there's juggernaut, stopping power, and double tap. I'm hoping for Bouncing Bettie's though. xD