Paint over the stringer makes it look like a opaque pigment tint, and for an old school fish, who wouldn’t want that? You could do what you suggested, but it would just create more work for you.
I would take down the stringer and with the block plane theres a high possibility that you will have issues when glassing your board, the glass might not adhere to the stringer properly.
Rick, John Carper makes a big point to say “Don’t paint the stringer”. His outlook is that the resin needs to soak into the stringer wood a little bit for a good bond, giving an “I-beam” effect and strength for the board.
Your call, but I’d clean it off it it was my board.
You’re talking Polyurethane/Polyester right?. If so, you can paint over the stick. The crystalization problem can be avoided by precoating the painted stick with some lam resin before you glass the board. Now if you’re talking about EPS/Epoxy, crytalization is’nt an issue, but dark colors are. One thing is that the weave of the cloth tends to show more. The other is dark colors heat up when exposed to the sun. So you might have some delam issues to deal with.
Yes, that is generally true. A lot of it has to do with how the paint is formulated, the quality foam you are painting on, how well you apply the paint and lastly how well you glass it.