First of all, I'd like to encourage Alex to link this build in the "GR Research Build Threads" sticky at top this of circle. Beautiful work and obviously inspiring to others.
Electronicsfanatic, let me see if I can shed some light on a couple of things. FWIW, I'd encourage you to have Danny's kit on hand when doing build. I've always found it helpful to have actual parts for driver mounting, test fitting, tweeter depth, crossover board layout, etc. You get the picture.
High density MDF, like Medex and Ranger are superior to any Big Box stuff I've seen. Higher density gives slightly better panel damping in theory but also workability is enhanced. Crisper edges and dados, better screw holding capability, easier to finish, etc. I find exactly one place that I prefer standard MDF and that's the spoil board on router because I pull vacuum through it. Look at real lumber yards, if you have any near you. Cabinet shops use it and some wholesale suppliers will sell to public. Contact manufacturer and find out who distributes in your area and give 'em a call. Also if we know where you are perhaps a resource could be suggested.
I don't think there's any place you don't want NoRez except holding it back an inch or so from backs of drivers. Foam layer can be removed in areas where it's in the way, like under crossover. On the other hand, good panel damping can be accomplished without 100% coverage. The damping layer and not the foam is doing most of the damping work and the performance difference between 100% coverage and, say, 70% would be almost insignificant.
Veneer can be done a number of ways. Easiest for many would be paper backed veneer. Raw veneer is more demanding of the craftsman. Books have been written on the subject. What's the cherry veneer you have?
From a woodworking perspective, my builds have always served to raise my own bar, which I like the idea of. Although I cut my teeth in cabinet shops, I've learned more about furniture building outside of that. Do and learn, do and learn...