1) Can u play dl planes in campaigns?
  yes if someone makes them i see some give it time?  to date i have seen 2 org aircraft and alot of repaints i wish M$ would put out the cfs2 AI sdk's so someone smarter than me can port them to cfs3 with gmax or even M$ do it

2) When playing a gunner in a bomber, i can shoot, but i cannot aim. The pilot of the plane also turns the throttle down to 0%. Why?
  I think bad code?  But i dont know that one

3) Why can't i play w/more than 4 planes in multiplayer?
   you can change your multiplayer opps to a T1 and have more if you host a game BUT i dont think that is the thing to do but thats me see my post (ZONE play)

In short i think M$ droped the ball but thats what i think