Alembic recommends using Flitz polish for the brass parts; I don't believe lack of polish will hurt them, it will just make them darker, and you'll always be able to polish them to the original brightness anyway. I use either Alembic or Martin polish for my basses. I'm sure you can easily order Alembic polish & Flitz polish through your dealer or through the Alembic store.
Without looking at it I 'm not sure about what can be done for your Epic at this time; if you can post some pictures of the trouble spot, I'm sure Mica will be able to make better suggestions; if the wood has already been somewhat tarnished by the playing, then refinishing might be the only way to get rid of that.
In terms of protecting the wood, cleaning the bass (even if lightly) after each session will definitely prolong the life of the finish; the best thing to save the look of the wood, is, obviously, not to play on it, meaning not anchoring your thumb on the body , but on one of the pickup covers; of course not everybody is comfortable with that, and some folks need to anchor themselves in a position where there is no pickup. If that is your case, then I'd say keep your hands as clean and dry as you can when you play and clean the bass at least in that spot when you're done. Sweat is probably the #1 enemy of finishes (possibly after belt buckles, but at least those are on the back).