Having worked with arrows IRL, I know that feathers are needed for the fletching (the three things at the back end of the arrow). Perhaps there should be an easy way to gather some feathers just by scaring the sea gulls or pulling them out of the water like scrap and planks. I think it would only take one metal scrap to make the arrow head.
With the bow, I know it might seem like rope is what you'd need, but bows actually require a finer material: string. Maybe a recipe for that could be added as well?
Wool seems unlikely on the ocean (because it comes from land-based animals), but maybe fabric scraps could be gathered from barrels? Cotton seeds would be another idea. They could be planted in crop plots.
All your other ideas are pretty solid, though.