i am VERY sorry to inform you of this, but you cant. in Halo 3, halo reach, and halo 3: complete multiplayer experience you can.
No.
you cant
You cannot make your own maps in Halo: ODST, it doesn't contain forge world. Halo 3, Halo: Reach and Halo 4 all contain forge world.
Yep.
muythic map pack. that comes with HALO 3: ODST
ODST does'nt have the AR.
Yes.
The Arbiter does not make an appearance in Halo 3: ODST.
in HALO 3 you are a Spartan and in HALO 3 ODST you are a Orbital Drop Strike Trooper (ODST)
On Kilowani Station. Which is the final clue.
Yes. There are at least two more. One is Halo 3: ODST, which is an FPS starring and ODST (it will also come with every multiplayer map from Halo 3.) The second is Halo: Reach, which nobody knows much about. Look for a preview in ODST.
yes only multiplayer has the new map packs but you can get them in the DLC
Halo 3: ODST will only be released on the Xbox 360. The are currently no plans to make Halo 3 or Halo 3: ODST available on any other console other than Xbox 360.