Hey there
just give a phew of my ideas

1.when you select a tank or a group of soldiers instead of the cheep sound "tie your F**KING shoe Conrade" have like radio chatter
2.you should have a look at tank def that shouldn't take up pop cap
(eg. Anti-tank turret)
3.sniper should come in two's spotter and sniper him self
4. you should have like a delta team that can call in a laser guild bomb or missile
5. have a asset that makes it able for you to call in a AC130 gun ship that would ace for taking out forts or building
6. it would be cool to have British,USA,China,Russians and maybe germany still ? or Europe Co instead of british and germany
7, you could add MSLR launchers to it
well thats all i have on my mind so far

hope i could of been a help with ideas side of it
p.s
im start learning how to make maps for this game
i looked into it
looks fairly easy, i used to do a lot of mapping on Hl2
and COD