1. How do you add new units in game after starting...
2. Can your army be as big as it was in Dawn of War: Dark Crusade
3. Will Relic ever realese an expansion to play other factions in the campagian.
4. Can you use alot of Vechiles (spelling) in the game

please help i have been trying to find the ansrews for over 5 hours!

The first DoW had like 3 expansions that added other factions and such, I'm sure eventually DoW2 will have the same. The single player, unless they give you the option to and say it, a lot of time there are no new units you can get in the missions, what they give you is what you have to work with. There are plenty of vehicles in the game to upgrade to as well. Lastly, no, your army cannot get as big as it was in DoW(especially in single player) because they made it so the fewer guys you're using are stronger and its more about being smart and using your units wisely, then just numbers beat other numbers.