Hey geof.....Fineline tape (good paint shop of auto body supply shop-expensive but worth it IMHO) works great for the intial edge on the masking then regular blue masking tape for the balance. Be sure that you have good adhesion to the hull with the tape so that the exoxy does not migrate/wick under the tape....the etoh alcohol cleaning will help a long with a good amount of pressure when applying the tape will solve this issue. The fineline tape will also help you to make nice clean curves to the epoxy area. The masking will also allow one to sand the area neatly, as you will have a line to sand to. Be sure to remove the tape when the epoxy is still somewhat green....big mess otherwise with a lot more work when you have to remove masking-maybe you want the blue pin stripping ;). The West system has good UV resistant so IMHO not need for a UV resistant coating on top of the west system. The graphite additive looks neato but it is graphite and continues to shed after the expoxy cures( take a pencil and rub in on your hand and you will see what I mean), and it is actually a friction midagating additive and may not be necessary in your case and application, IMHO. Never tried the credit card application techinque but it makes total sense to me in "lou" of the roller  and or brush application. IMHO I dont think that I would fade out the edge via sanding, the edge height will be a function of the epoxy coat thinkness. As far as the second coat it is up to you and your intentions of this project-if a second coat is applied expand the second coat area outside of the first coat-this will help the fade out and the edge height=be sure to sand again before the second coat as the first coat will have a film on it as part of it's curing process. The point spoken to in regard to the core is similar to the kevlar fabric taking on water, I am not sure about the material the core is constructed out of....in Bell's it is a spun synthetic fabric or a rigid foam depending on the  lay-up and lay-up method. Remember water is heavy and an oxidizer and keepin' the water out of the lay-up is a good thing. I am all for West as I have not had a bad experience with the system and have used it quite a bit, the slow will be stronger as you have been informed. Hope this helps. M