+x+xI like to use tow. Generally I'm doing carbon, but no reason fibreglass rovings wouldn't work the same. Just dip in a pot of resin and squeeze the excess off with (gloved) fingers before running it around the edges. Quite neat and easy, resin and gelcoat can be a bit fiddly to get a consistent coating and then there's no strength to it either.
Would recommend masking off the adjacent faces to minimise clean up later, and if your parts are large then this could be a bit of a pain. But works really well for smallish parts, it's what I do on wing end plates etc.
Yeah that could work, I might use a bit of spread tow/tape instead as the core thickness is 10mm.
It's quite a large panel as it's 2.5m x 1.5m so could be a bit of a pain doing it that way but at least it would be structural.
The spread tow tape is a little bit trickier, it doesn't work as neatly as the loose tow. Admittedly I haven't tried it on a flat 10mm thick edge, generally only larger radiused edges or smaller flat edges. so it's worth a try. But I suspect you might find it a little messy and tedious.