An argument for both a pale gray or a black primer.
A dark primer could give depth to the wood finish, but the underwater bottom finish of ships in that ear was an off-white, which might not cover well over black. Your pick.
Depending on how you want the deck(s) to look, those often can work best as sub-assemblies that you finish first, then install within the hull.
Generally, things like guns, masts, yards and the like want to be subassemblies. (I never, ever, assemble yards to masts until the masts are stepped and at least partially rigged; the bare spare are much easier to work around; I also only build masts in their individual assemblies, too--that's me).
For significantly less than 2¢ I'd skip the vacuform sails.
For one, there's a "tradition" that warships are not displayed with sails.
For aother vac sails are a giant pain to work with, and have detail on only one side, and are often no where near the right size.
You will have to judge if you are hapy with the plastic shouds and ratlines. I find them off-putting next to forestays out of thread--much in the way a biplane rigged half with monfilament and half with 1/32 wire would be offputting.