Yes and No....
For now, the only reveal of "weapon customization" was skins. 343 has confirmed it, but no details released.
halo 4 limited edition, comes with a copy of halo 4, a T-shirt and special armor customization.
You pre order the game
You cant dude...this is not COD
select it as a weapon in your loadout editor
it is a halo weapon used in the games halo 3
With a weapon in Halo 3
both
Dying
Yes. The sentinal beam is a weapon.
The Plasma Pistol
No, Halo Reach occurs much before Halo 4. In the timeline of the actual world, the games go: Halo Wars Halo: Reach Halo Combat Evolved (And Anniversary) Halo 2 Halo 3 Halo 3 ODST (Same time as Halo 3) Halo 4
halo in the game or film is a alien weapon that has an ability to destroy galexies