I asked this question of a D1 coach. He said it was a gray area, but governed under the 'camp' guidelines....sort of an ongoing, personalized 'camp'. The coaches could get into trouble with the NCAA if they turned down too many, or certain types/ages of players and the lessons were therefore seen as tryouts, although that seems to rarely happen. He also said that if the NCAA had a problem with it, the penalties would be on the coaches, not the players.
With regard to contact regs, if the player contacts the coach for a lesson, not vice-versa, and goes to the campus for the lesson (or any other reason), pretty much anything can be talked about. The theory being that the impetus came from the player.