They do the same thing they did in Halo 3. You can "activate" any of them during campaign for different effects. For example, the "Grunt Birthday Party" skull makes an extra sound effect and confetti whenever you kill an enemy with a head-shot. Unlike halo 3, you do not have to find them this time around.
There are no skulls in Halo Reach.
No. You are given them all.
You click on the tab that says skulls and you click on the skull.
practice practice practice :)
No, only Oddball.
You can, just like in Halo 3. It will have more skulls in it too. I'm not 100% sure what all of the names are and their functions, But I will test it VERY soon.
I don't believe you collect any. You just turn them on or off.
In the wave options when customizing a firefight game.
So far, the datapads in Halo: Reach have no function, but it is possible that, as they did with the skulls, Bungie will add some type of reward or mini-game for them to follow.
yes, you can make custom skuls in at the very least firefight mode.
Search for Halo 2 skulls on www.youtube.com and there will be a selection of videos showing the wereabouts of the skulls or how to get them : )
When you have the skull menu brought up, click on the skulls you want to activate to activate them. Simply, move the control stick to the skull, and press the button.