The paint is easy. Tape off and carefully roll/ brush.
You will find that if you remove the trim and finish each element (trim and cabinetry) separately, the painting and the varnishing will go much, much faster and the result will be far better. You may also wish to give the cabin a really good vacuuming before starting any finish work. Wait at least an hour before applying finish after vacuuming, to let the airborne dust settle. For the same reason, close all the hatches and ports while finishing and leave the boat immediately after applying the finish. In colder weather expect drying times to double.
I would not roll/brush....it's more time consuming in the end for this small a job. Interlux Brightsides flows out beautifully with just a china brush. Just lay enough paint to cover the cabinet and resist the urge to cover completely in one or two coats. Figure on 4-5 coats for a primo job, sanding with 220 and tacking between each coat.