No they won't.
yes halo reach will have custom games. it will also have an amazing campaign, all kinds of game modes for matchmaking and custom games, and the thing i am most excited about it will have firefight with matchmaking!
You can if you are playing offline or a custom game, but skulls are removed from the maps in matchmaking
yes you can, Firefight will however be different in matchmaking then in a custom game. The match will usually be on Heroic difficulty and will only be 1 round. but yes you can play with random people in firefight matchmaking.
The only elephants that are driveable in the game are in the custom game: Sandtrap; this map will not be played often on matchmaking so dont look for it there
Only if you start a custom game and invite friends, but not online like a matchmaking match.
you can only do it thought matchmaking on double xp weekends or by hosting a custom game with your friends.
no
Choose the gamemode Slayer (Not Classic Slayer) and play that one, or choose invasion, to play Spartans against elites, or choose infection, for Spartans and elites to fight infected Spartans and elites. there may be other ways, but they are not yet known.
Mario is not a playable character although you can play as him only as a custom character using game maker 8.
Either get wifi or ethernet hooked up to your xbox and go into matchmaking or for two player offline just go to custom game.
On the first screen you see before going in and seeing "campeign, matchmaking firefight, custom game" etc. click campaign. It will automatically have the map you left off on.
How many elites did you take out in the game.