OK here are my suggestions after playing for a day: Use the upgrade pack Grunts from Blueshift for the Marines, More Zombie Models, Cooler boss guy than fred available, and better radio things, these ones sound like admiral Ackbar from Starwars, heh

All of these u can do urself. Marine mdls, jus dl the HD pack for it, i dont think MORE zombie mdls r gonna be happenin as this is the game engines limit mayb the only way u can get new ones is if u dl a skin pack from Rusty ir anyone else out there, well for Fred ur gonna hav to wait on that, for the radio things u can just make ur own. I did, its simple but u need a mic or get it off of movies or somewhere that uses radio commands. Once u get that take out a audio file in the sounds/radio folder, insert the audio file and rename it, IE: take out ATTACK file, make ur own audio file, rename to ATTACK, place in the folder. Now u hav ur own radio command. U can do that for all the ones thast wrk.