Well to start we could make things in lower case letters.
I'm not sure how useful you'll find this guy. Because he's in Terminator Armor he'll move very slowly and probably won't get in combat with any targets that are overly worthwhile. You may want to give him the Mark of Tzeentch and Daemon Weapon instead so he can at least Deep Strike and do some damage on the turn he lands.
This unit's probably a bit small. If you lose a single model, no matter who it is he's going to be expensive and important. Add at least a single extra body to help catch bullets.
I really wouldn't take this unit. It's just asking for trouble. The plasma guns will only make it easier to take this unit down.
TROOPS
Good, though I think you could do with a Champion armed with a power weapon. These units are expensive but they'll do a LOT of damage.
As above.
Best choice in your list, imo. Be sure to split these guys into 3 seperate squads.
Good luck,
Katie D