1). When building a human settlement, remember that while individual houses are nice, the first thing that should be built is a communal hall. Build one up and put some beds in it, keep a free area. This'll help with the migrant versus construction rate. The communal hall can also serve as a (realistic) meeting area and meeting zone.
2.) Communal housing can save you space; set up apartments within a building, have a dining room in it with some food storages. This keeps it nice and neat.
3). Everyone is a carpenter or a mason. If there isn't something pressing, put them to work raising walls and spend their time roofing. I'd also start up and work down, instead of the more realistic way: Build a few supporting walls in the corners, and a ramp going up (ramps save time so you don't have to build both upstairs and downstairs), and build the roof. You can build rooms even if there aren't any walls, even though they might complain about the draft.
4). Humans drink water, booze fucks them up and slows them down. Wells'd do you good, and keep your humans away from the river (which is probably why the carp are so fierce--because your fishermen aren't the only ones on the bank.)
5). Walls are awesome. But you know that.
These are some pointers I can give you. I've tried the above-ground fortress with Dwarves. You can build underground, carve in each house and building a cellar for storage. This'll keep your miners trained (somewhat) and give you stockpile room so you don't have to build gigantic warehouses for EVERYTHING.