SPECACT is the uniforms I was refereeing to. They are basically camouflaged weapons (yay?) and new badges and achievements. I really could care less about that in light of more pressing things.

The "Infantry only mode" refers to the ability to remove vehicles from the game (or your server at least).

EDIT: ill expand on all those things:

-A new map usually means they take a map that was used for say Conquest only, and make it into a RUSH map. It's really a new game mode on an old map. (is that worth calling new? I dunno discuss).
-The new Chat mode is being able to type works when you're dead. It seems like a no brainer, but when you die you CANNOT communicate.