It sounds like you're getting a bit obsessed with the subject. While I can understand and empathize (I went through it too), it's something you need to get past. The best advice I received when I was obsessing over my first SOF (the gunwale wood, in my case) was: "Just buy some wood and build a boat." Part of the allure of SOFs is that they are as much art as science. You have to be willing to surrender to the process and let it flow (as a former Q/A Engineer, that was very hard for me to do). While an understanding of the technical aspects of boat building is important, developing a feel and an eye for it may be even more important. It may sound somewhat goofy and "new-age-y", but you sort of need to "think like water". Trying to make your first boat "perfect" is a fool's errand; it's not going to happen. Every SOF is a learning experience and you need to approach it that way. Just let go and do it; everything will work out in the end.

Now, to your specific question:

First off, there is no "perfect" or "ideal" skin material or finish. Everyone's needs vary, whether it's due to the way the boat will be used, cost considerations, aesthetics or a combination of these and other factors. You need to assess your needs and buy accordingly.

Second, a variety of fabrics and finishes will produce a satisfactory kayak skin. If you've been reading this forum, you've seen that people have used polyester, nylon, cotton canvas, vinyl, hypalon and other materials for their kayak skins. The fabric weights have varied from 3-15 ounces/yard or more. They have been coated with oil-based paint, oil-based varnish, water-borne varnish, 2-part varnish, epoxy and rubber coatings like "Snow Roof". All of these work when used properly for a given application, but none are universal.

What I would suggest is that you just go with a basic, "foolproof" system for your first boat. Pick a nylon or polyester fabric in the 8-10 oz. range and coat it with a good 1-part varnish like Zar exterior oil-based varnish. The fabric will be easy to sew and the coating will be easy to apply and maintain.

That will get you on the water enjoying your boat ASAP. Once you've spent some time in it, you will learn a lot about SOF boat characteristics and those of the skinning materials you used, and you'll be able to make informed decisions about any changes you'd like to make to this boat or the ones you will build in the future. It's a process, not a destination. Just go with it and enjoy it.