Good to see the letters on the map now.
First one is the Multiple Rocket Launch System (MRLS): http://en.wikipedia.org/wiki/Multiple_rocket_launcher
Seen in the Thunder Run Singleplayer Mission. Sure they will be noob friendly but not doubt really weak. If used right they will be dangerous but then so is any weapon/vehicle in the game...
The other 2 are crosses between the MBT and the APC's --> APC with MBT main gun on it. They are tank destroyers with weaker armour but the same offensive capability as MBT's.
That makes the 5 new vehicles the 2 tank destroyers, the ATV and 2 MRLS's. Then of course the AC130.