... it's the responsibility of the person entering the interstate to merge into traffic. So he should make sure that he doesn't just expect people to let him in or change lane for him.
I would strongly second this point. It's important to keep in mind that people on highways often aren't paying any attention to those merging onto the road.
Another thing that can be tricky (and this very much depends on what region you're in) is changing lanes, especially on a highway. In some areas, people like to leave plenty of room between vehicles. In other areas, they're happy with a couple of inches. In my experience, it's the latter who pay more attention to what other cars are doing, and are more likely to switch lanes to let you in/out, etc. But don't count on it.
Overall, as other posters have said, it's relatively easy to drive here, because there's plenty of room and things tend to be well-marked. There are very few roundabouts (although, mostly, Americans still don't know how to use them, so you'll see an awful lot of people treat them more like 4-way stops.)
One last note (which may have been in the hints you've already found): Speed Limits. Although, personally, I fully recommend strict adherence to the posted speed limit
(and it's almost always posted, at frequent intervals)....most people treat it as more of a baseline. Honestly, you should drive at the speed you're comfortable with, even if that's below the speed limit. But be prepared to be passed by almost everyone. The actual speeds tend to be 5-10 mph over the posted limit, whatever that limit is. Sometimes it's even more, particularly on city bypasses, etc. Also, once you're at a comfortable highway speed, if your car has cruise control, use it. Most other people do, and few things are more annoying than following someone who keeps changing speed.
