Good idea.But C&C/RA voices wont be pretty usefull as they sound too simple.
You could also use sounds from games of other Universes,like StarCraft/BroodWar,WarCraft III Reign of Chaos/The Frozen Throne,etc.
TS Sounds are nice but there are only a few types (like RA2-plain,they are used for a lot of stuff,however Firestorm adds a bit more to it
)
RA2(plain) use Generic Voices and YR has all sorts of sounds that can be used
Erm..."mike"...i ashure you that you cant do anything by using a plain mike and Sound-Forge or any other sound editor