"Escape to Salvation" - "Magnificent Retreat" [Campaign 4, Mission 4]

1. Yes, with him, completing the game turns into an easy walk.
2. I gave him to the Dwarf, and there were no problems with the battle.
3. You can only play the 4th mission as the Orcs.
P.S. The most difficult battle for me was the one for the Sorceress in this mission, and the difficulty was, of course, Hero.