yes
you get one xp per win
You get XP by winning matches in matchmaking. If you lose the match, then you lose XP. Simple.
win, and go positive for that round... is that really how you earn xp ?
You get a few extra as a victory bonus
halo 2
Halo: Combat Evolved runs just fine on Windows XP.
Yes. You can.
No, They don't have a bot match in Halo: Combat Evolved, Halo 2, Halo 3, and Halo ODST. I don't think they will have on in Halo Reach
not legally
no.... can't be insall on win xp
halo 3 odst, unlike halo 3, has no matchmaking, sorry
By gaining XP