Good thoughts. Basically, all of the returning freshmen and sophomores and incoming players will need to continue to work on understanding defensive effort, positioning, and help defense. That was a huge strength of the guys leaving.
The other thing I'll add is that it would seem that everyone needs to get ready to push tempo and play aggressive defense. This team is going to play differently than it did last year due to the differences in personnel. I think we'll run more and I think we'll apply more pressure on defense.
Aside from that, my comments on/additions to your list:
1. I'm less concerned about Mason bulking up. He's pretty big already. I'm more interested in the second part, which is how he develops his game. Will he get more comfortable in creating for himself when given the ball on the block or on the wing? This year, he was largely a "catch-and-finish" guy rather than a guy you handed the ball and said "make something happen." Based on the discussion of his skills coming in, I hope he progresses in this regard.
2. Miles: work on that jumpshot, work on defensive footwork and understanding of positioning on offense. He just needs to get to a point where he isn't trying to rely solely on his leaping ability to make things happen. If he can learn to be in the right spot, life will be much easier for him. And his athleticism will make more things happen for him.
3. Dawkins: work on decision-making with the basketball and confidence/ability to handle the ball.
4. Kelly: get stronger and get more comfortable with the speed/strength of the college game. He's got the skills and basketball IQ to be an impact player. He just needs to catch up phsyically.
5. Smith: assume the leadership role (even moreso than he already has). It's going to be his team next year if Singler goes, and he's going to need to help the younger/new guys understand what the team needs to succeed.