The most difficult part initially for him will be turn lanes - often a major left will have two left turn lanes, the one nearest the straight lanes is the slower, the one by the middle of the road is the faster lane.
If you are turning right at a set of lights and the lights are red, and you are in the lane nearest the kerb, you can treat it like a normal junction, just pull out when clear. UNLESS there is a sign up hanging with the lights that specifically says 'no right on red' or it is an arrowed filter light (i.e. red arrow).
on the interstates you just have to keep your wits about you as the outer lane (what we would consider the slow lane) will become the exit lane for the next exit. watch the signs overhead, when you see one just make sure you shift into the lane UNDER the place you need to go - the US system works this way rather than having separate slip roads.
Apart from that, relax and have fun! I love driving on the US roads, much prefer them to over here