Thanks for all the help. Now is the time to start working on the kayak deck.

If it were my project, I'd work on the (minimum) structural necessities, and leave the cosmetics till later -once I decided (after paddling it, and having some experienced paddlers test-drive it) that the boat was worth 'saving'.

My first priority would be to give the fiberglass tape joining the hull & deck on the inside a good look. How much of it is separated? Can it be removed and replaced, or are some failed sections unaccessible?

Next would be to build a coaming and paddle it.

Then, I'd look at the cosmetic issues.

Do you plan to keep the 'wood look' on the deck, or are you going to cover with paint?

If you think you're going to paint it eventually, you could just remove the loose flakes, give it a good wash and coat it with epoxy (resin+hardener) or even 2-part epoxy primer from the auto body supply. It won't fall apart in casual flat-water paddling.

You could build a new boat from scratch in 100-200 hours, if you didn't get carried away with artistic efforts. Start your timer on this project!