You can't drive a pelican in Halo 3.
press x
U Cant
in halo 3 there is none to drive
you cant
to stay on a pelican i keep on pressing x, but to jump on it, i have no idea
pp
Sorry but you can't fly one.
No there is not a mod
Yes and no. You cannot make it explode, but you can make it fall into oblivion with a well placed plasma grenade. There are videos on youtube demonsrating this.
A Hawk is not from Halo 3 it is from the game Halo Wars which is not associated with Bungie. Halo Wars Ensemble Studios created the Hawk. You may be thinking of the Hornet or Pelican.
Not until Halo 4 you can't. By the way, in Halo 4, you can FORGE a pelican! :D