Rumors that Hansbrough is going to do the same, but I expect at least one of the two to return.

Smart move.

When do they have to pull out of the draft if they decide to stay in school?

link

He's wise to test the waters, but unless he improves his current stock, he should be back. Most boards I've seen have him top 10 next year. That's a lot more money.

Lawson leaving unc wouldn't surprise me. Some have said that he left right after tipoff of the KU game.

Whether they go or stay it's immaterial to me.

I figure that Ty has had this on his mind for a while and my not have his "whole heart" in his books.
(However, I'm sure that can be worked out).

ANY player with a snowball's chance of getting drafted would be wise to test the waters. At the very least you get evaluated by NBA teams and if you're not ready they can tell you what to work on to get ready

I'm sure JJ Hickson has been studying hard since he declared himself eligible for the draft.

He and Lawson are study partners.

I read that JJ is indeed attending classes now and will this summer (this is from PackPride). He won't be going on the tour of NBA camps. His evaluation will take place in Raleigh and only one team is scheduled to take a look at him (this is from gopack.com, iirc).