THE halo games that have the flood are halo combat evolved,halo 2,halo 3 and halo wars
Yes.
No, the only teams you can be in Halo Wars are the Marines (humans) and the Covenant.
No.
its possible
covenant & flood
No, there is no flood in Reach. With the expception of halo wars the flood was not released until halo combat evolved where the humans stumbled across their existence in search of a lost platoons distress beacon.
because they are weak and they can't build stuff
you cannot be the flood in halo
In Halo Wars, only the UNSC and Covenant are playable. However, I think there is a mod being created which adds them into the game.
They look a little like flood versions of trees. With fleshy sacks on them. There are some off to the right of your starting base.
Halo Wars