Dominions got human races, yes. Most of the races are humans, or consist mostly of humans. There is no ork, orcs or somthing whit that name. But there are plenty of big, huge strong beings, like jotumhein the giant race.
The farrest you can get to anything reassembling a ork from warhammer is to summen a troll and cast mossbody over it to give it a green skin.
And about big battles, most of them involves from about 100 to 300 units on the battlefield. I never tested what the limet was, buts its possible to have
1600 units on the battlefield and maby even more.