Buses are the way to go, obviously. When you get dropped off at the start, understand that there's nothing there but bag check, some portajohns, and (I think) some water. There is no shelter if it's raining, so be prepared with poncho/umbrella, etc.
Two Harbors can also be considerably colder than the rest of the course - even if it's forecast to be a hot race, carry more throwaway stuff than you think you'll need.
Post race, you'll have to cross the race course to get to the buses back to your hotel/dorm if you're not staying at the finish. It's always a bit awkward. The buses back can be hard to find (on the opposite side of the DECC) - doesn't hurt to include a map of the finish area in your checked bag.
The race start may surprise you a little - last year there was no "on your mark," etc. The horn just went off. So if you hear silence a few minutes before race start, don't assume that means the start may be delayed slightly.
Course is very gently rolling - not flat, but just enough variation to shift the work among different muscles. The road does meander, and sometimes groups just follow the median - avoid that temptation and take care to run the tangents.
The mile markers are impossible to miss - marked with balloons (different colors for half and full).
There are two notable hills - Lemondrop (which looks worse than it is) and the unnamed one that comes just after, when you turn right and then left to get onto Superior Street. The second hill is steeper than Lemon Drop, but shorter. It's not awful, as long as you're not surprised by it (as I was the first year).
Due to construction, the course detours at around mile marker 24. You make a left, drop down very slightly, run for about 1200m, then run up a slight incline to rejoin the course. Last year was the first year for that detour, and it wasn't bad at all. I thought it was preferable to the original route on Superior Street, which was pretty chewed up and rough.
The last mile can be tough - once you cross the bridge and drop down onto the waterfront, it seems like you just keep turning and turning, with no finish line in sight. Know that once you drop down, you'll make two left turns, and then two right - just count them down. The left turn just before the big boat is about 1200m from the finish; the right turn just after the big bout is about 800m from the finish.
There will be a clock at mile 26 (there was last year). You won't see the finish line until after the clock.
They will have several big arches of balloons as you approach the finish. Do not get excited - those are not the finish - the finish arch is much lower in height.
This is a fantastically well run race, and a great choice for a marathon.