Hi John,
I am just coming out the other end of this process. A couple of suggestions that have worked for me:
1. I would start with 120 grit. I am using aluminum oxide paper which lasts quite well. You can go across the grain (when sanding the epoxy - esp on the bigger 'blobs'). Just make sure your last go on the 120 is with the grain.
2. I then move up thru the grits to 180, 240 and finish with 000 steel wool followed by a good acetone wash.
3.The tape for the join will overlap the cloth already on the hull and deck, but will , assunming 4oz here, 'disappear' when resin is applied.
4. I have the kayak on its side so that the resin has "less" tendency to run. You will need to keep an eye on the resin once applied ...say for the first 1/2 -1 hr. Don't be afraid to be vigorous with the brush when feathering the resin.

This method has worked pretty well for me. Good luck with your next steps.

Peter Widders