in the antiques business patina is everything, polishing brass is a big no-no.
to restore the wood tthey would use meths and a very fine wire wool to remove any dirt and loose or flakey varnish, then wax with a beeswax polish.
having said all of that - its a boat, its your boat, so do what you want, its going to be in a harsh marine environment, so if you polish the brass up, you will need to regularly repeat, if you varnish the wood, it will still need regular maintenance, just to keep it in tip top shape. (to be fair, even if you dont polish and varnish, you will still need to keep on top of it.