Why not, his CT does not seem to have any limits. If he thought Kenjaku was alive for some reason and a funny scenario Kenjaku coming back to life is possible.
From what was said, Gojo's CE amount is above average, but not massive. He will just never run out so he can freely spam his best and most destructive stuff.
Well no. While Yuta is strong, this does not prove he could have beaten Kenjaku in a straight fight. Cause someone else used their technique so Kenjaku would not sense Yuta allowing him to ambush him.
They probably sent Yuji cause he's part of the next wave of their plan with Higuruma. Maki and Yuta still need to stay behind in case the plan does not take down Sukuna.