The Halo Reach Beta will include four maps. You can read about them here.
there are three
maybe
You can download Anniversary Maps to Halo: Reach but not to Anniversary.
Go to forge and make a map and then you go to the menu and slecte add map in halo Reach
YES! Halo reach has a "Forge" feature, which allows players to create maps, the reccomended map is forge world.
on halo reach you go to main menu and select forge and then select your map there start building your own map and i recommend forge world
that does not exist
Forge World.
At the moment there is no map that has the Elephant.
Forge is not in Halo 2 and comes out in Halo 3 and Reach
you cant get the default map cage in halo reach but you could try to remake one for your self
Halo: Reach comes with a built-in map editor called Forge Mode. You can access this from the main menu of Reach.