A few suggestions: Unless you are looking for a certain look, I would not stain. If you want to spice up the look, consider a veneer on the end of the blades.
Don't use wood filler. It will give water a place to collect and cause damage because of its porous nature. Instead use epoxy. If you need to fill a larger area, there are powder additives that make it stiffer.
You don't need any poly. Just use epoxy for everything. You can get west systems epoxy at West Marine next to West Town mall. They have fast and slow set hardners and also the pumps that measure the correct ratio for you.
I dont have a good answer about the cloth. Lighter seems better to me, but maybe not worth ordering if you have to get a minimal amount.
I swore last year that I was going to do it this year, but they still sit there in a pile.