There are at least two companies making kites to pull ships:
* skysails * kiteship * kiteforsail
With a two rope kite you can have it pull you to the left or right of downwind by maybe 75 degrees. So you can use it to pull you in the direction you want if you are mostly moving in the direction of the wind as you might with a migration. A computer can control the kite. By adjusting where it is in the sky and if it is moving back and forth the computer can control how much it pulls and what the average direction of pull is.
A sea anchor can slow down a seastead. Could have a rope with many small sea anchors so that a computer could adjust the drag by how much rope it let out. With no kite, the wind on a Tension Circle House might push it faster than a Pipe Spar with a kite. So for a group of different seasteads to travel together sea anchors would be good to have. Also, some seasteads would need sea anchors to go slow enough for an annual migration.
A fleet of seasteads with kites and sea anchors might want their computers to be able to communicate so the whole fleet could move in formation without bumping into each other. Imagine 50 seasteads with kites dancing in unison making figure-8s across the sky.
Force from kite
Skysails says their kite product line provide around 8, 16, or 32 tons of force in the direction of movement for their rating conditions. Their rating conditions are 25 knots wind, 10 knots movement, and wind at 130 degrees. We are probably more like 16 knots wind and 1 knots movement, but that should be about the same force.
There is a some angle, maybe 40 degrees above horizon, and swooping back and forth in a figure-8 that gives the optimal pull. When they want to winch in a kite they keep in rather still almost directly above so it does not pull so much. It would be possible to generate power with the kite going out at the optimal pull conditions and using much less power to winch it in at the optimal winching conditions. Given the large forces this should be substantial.
In a ship you may be able to use the movement through the water to turn the propellers and from this a generator.
Either way you would sacrifice some of your speed but this can all be worked out with the proper sizing of the kite.