Yes
Yes
You get an achievement and if you have halo waypoint, you get the CQB helmet. Well you actually get it on heroic but you get what I'm saying. You also get an attachment if you've completed halo 3 on legendary too. Hope this helps!
beat the campaign on heroic(might as well beat it on legendary),and go on halo waypoint(u need xbox live)
no you will have to complete the campain on heroic
Yes. As long as you beat each level at some point at heroic difficulty or higher(legendary).
Halo 2 does not have a legendary ending. It is the same ending as if you did Halo 2 on easy, normal or heroic.
Well there is flightshoulders,body,and head.And you get them by: body: complete "Travo Highway" on either heroic or legendary. Shoulders: complete "The Ark" on either heroic or legendary. Head: complete Halo 3 on heroic or legendary.
you have to colect the skulls or beat the game on legendary, heroic, normal those are the three u hav to beat the legendary u get the e.o.d armor (awesome) skulls (hybusa and more ) normal forget) heroic (flight armor for elite)-
you need to finish it on legendary to see the legendary ending and to get the skulls. Heroic dont count.
you can do it on normal, heroic, and legendary, but not easy
You do not have to do them in order, but you must complete them all on heroic (or legendary) to get the acheivement.
It depends on what difficulty you play on, Easy, Normal, Heroic or Legendary