"what size is the line that hooks to the halyard cables for hoising the sail, and how many feet are needed. "
About 6mm should do it and the whole halyard should be twice the length of the mast [plus a couple of feet]
The 5.2 use a cable halyard with a ball hooking into a fork at the top of the mast (same as a hobie 16). So the line part of the halyard is only one length of the mast, not two.
