You will have a rock hard surface, so when you do sand the varnish for a re-coat, you will have a hard surface to sand to. Varnish sands away easy and you can sand right through it fast.

The 2nd issue you refer to is; generally if the weave is showing under the epoxy, your epoxy was not warm enough to fully wet out the glass or... the glass was not a good epoxy compatible type. Normally under good circumstances, the weave does not show. I have an old boat with weave showing and I have just learned to use thin epoxy that's warm and I buy my fabric from people who sell kits and know the fabric is good for epoxy wet-out.

Jay, thanks for the added info. I had not thought as far ahead as what I'll run into when I re-varnish it in the future. I now see that if I've already sanded down to the glass it is likely that I will then sand into the glass when preparing to replace the varnish. Reapplying epoxy now sounds like the better option. Most of the glass I see now is on the deck where I've feathered the outside sheer glass, especially on the flat aft deck.

I'm pretty confident that the materials I used are appropriate - 6 oz glass on the hull, 4 oz glass on the deck, both from Raka, System Three Clear Coat (very low viscosity) for laminating and System Three Silver Tip (higher viscosity) for fill coats. The weave was not visible until I sanded down to expose it. Temperature is another matter, as conditions prevented me from getting much above the manufacturer's minimums. I did heat the room while working and overnight after applying epoxy, and I keep the epoxy in a box with an incandescent light bulb lit all the time.