The wood blocks below the valves are not glassed in. They are recommended/required by the valve manufacturer, Blakes.
The valve hull apertures are round 8" below water level. Ideally they should be lower, but the locker gets narrower lower down and there would be insufficient room for the valves. It was a compromise. It means that when the boat heels to port, the fresh water intake aperture is likely to be out of the water.
I tend to be in a marina at night rather than anchored, so cannot claim to have made massive use of the loo, but have not had any trouble. Overall I like it a lot, and am happy to recommend it.
A further comment on the valves. I opted for the Blakes seacocks/valves, because they are compact and I could fit them lower in the locker than with the flanged thru hull fittings and ball valves. But I thought they were very expensive, and I was disappointed that are now were made from DZR (dezincification resistant)brass rather than bronze - no real evidence but DZR sounds new fangled and not as good as bronze. Also the traditional design means that lots of laminate edges are exposed where the holes are drilled through the GRP, potentially allowing water ingress. They valves make no attemtpt to seal against this, whereas the flanged fittings aim to seal on the outside of the hull. I tried to overcome this by painting all surfaces with epoxy and then using lots of marine sealant when fitting the valves.