Definitely.
beat it up
u just nead skillige and kill the covenant bro!
Google, Halo: Reach mission 7 exodus walk-through. There are plenty of sites that can help you.
No.
beat the campaign on heroic(might as well beat it on legendary),and go on halo waypoint(u need xbox live)
Yes, Mario2903 plays Reach, infact he beat the Campain on Normal.
Not possible, unless you have beat the game and want to replay the levels
go and eat some kfc then try or just get better at the game??
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!
The Persians
No you are supposed to die eventually. That's why it has such a good death animation/scene for when you die.