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

Hello everyone, I have 3 questions: 1) Is it worth leveling up Zehir's spellcasting skills in this campaign? 2) Which set is better for Wulfsten: the set of the Dwarf Kings or the set of Saar-Iss? 3) Is it possible to level up Kujin without replaying the entire Orc campaign (i.e., by completing only two missions)? Regarding the third question, I'll be honest: I don't feel like replaying the entire Orc campaign.