I think the right-turn on red has been covered now ;-) The 4-way stop is always a tricky one to get right. Just make sure you come to a stop at the line, and then go when it's your turn. It seems to be a sort of instinctive thing as to when you go, but it's the person who got their first has priority. On the Interstates, you can freely pass vehicles on either side, so just do whatever speed you are comfortable doing in whatever lane you want. On quieter stretches, the general rule is slow cars keep to the right, but you can still pass on either side. Also, watch out for Interstate exits, as they can be on either side of the road, left or right!
White lines divide lanes of traffic travelling in the same direction, and yellow lines divies lanes of traffic travelling in oposite directions, but other than that, it's like the UK, where you can't cross a solid line.
Never, ever, park in front of a fire hydrant.
Always stop behind the school bus when he is stopped with lights flashing and the stop sign out.
Don't flash your lights to let someone out at a junction, as they don't seem to do that at all in my experience, they just seem to slow down or gesture with their hand that they are letting you out.
If you need to change lanes, indicate in plenty of time and move into a gap. Again, they don't seem to indicate that they are letting you out, but if your indicator is on, and there is a gap, then just go for it.
In Florida, always drive forwrds into a parking space in a car park (except theme parks), as they only have number plates on the rear, so like to be able to read it from the roadway. Some car parks have signs saying this, others don't, but I've got in to the habit of doing it everywhere just to be sure.
Can't think of much else at the moment, hopefully that is of some use.