Mike,
Your questions are not stupid at all. It's my experience - from myself and others - that leaders and tippets are complex and quite intimidating and can be difficult to understand and master.
1) Sealing the knots in some way makes very good sense. I know the problem with the knots picking up weed. I don't know whether the UV glues would work, but they probably would. Loon has its UV Knot Sense, which I personally use for flies, but judging from its name, it should work well for knots.
2) I usually tie my leaders with the intent of adding a tippet to the last piece of the leader. I then work my way into the tippet as I change flies, and finally cut off the last bit and tie on a new one. This slowly eats into the leader itself, but it takes quite some time before the leader is "worn down". I can always replace the last bit of the leader before I tie on the new piece of tippet. The tippet ring will enable you to almost endlessly replace the tippet without eating into the leader itself. I have actually bought a handful of rings that I want to use on my leaders for the exact same reason.
Martin
