re: Closest boat launch to Fairview St park?

Private property, I'm almost certain. It was used as an equipment staging area for a while during the seawall construction and got fenced then. (You used to be able to drive to or fish from the west end of that spit of land looking towards the lighthouse.)
After the construction was complete, they put in permanent footings and piers on the houses. The "big" house was on cribbing for a long time. The house to the right/north is new construction. Or new to that location, at least. If you look around the parking lot and the first 1/4 mile or so going out, there's a wire fence with "posted" signs. I'm pretty sure it's all private ownership.

Speaking of signs, look about 15' up the light poles in the lot. There are signs about the parking regulations up there. I don't know how strictly it's enforced, but they've been up there at least a year or two. Sometime after the new seawall was built after Isaac, which was Aug., 2012.