Forgot about Derosiers - he's a solid addition. I got the chance to see him play quite frequently when he was in high school, and although the competition wasn't the stiffest, he exhibited an advanced skill set for a center his age. He had a nice touch inside the paint, and had the ability to step out and knock down threes. He struggled at Wake Forrest, but it's unclear how much of that can be attributed to the horrific situation he was thrown into. With some added muscle and confidence, I see no reason he can't at least be a solid rim protecting center off the bench who has the ability to go for 10-15 points occasionally.
As for Dunn, your season may well hinge on his development. He did a lot of nice things a year ago - he was a plus defender and excellent rebounder, but his offensive game lagged behind on the development curve. I believe you'll have enough in Henton, Batts, and Cotton to dance with or without major offensive contributions from Dunn, but you'll certainly need him and Austin to play with poise beyond their years if you're expecting any sort of deep run.