Well theres nothing to learn in use for... i mean i could show you 1 use for vector product, and i could fill a 1000000 page book of them but id still be scratching the surface.
vector product, clamp, set range, average, multiply divide. They are just mathematical operations that are well documented in the manuals, and maths textbooks. Theres no way anyone can tell you what you can and cant do with math. But as i said the real gems for such knowledge is basic 3d theory and it comes from many sources. I recomand actualy learning vector maths and then looking at what some of the big sites do with theese... indeed theres a cool explanation of how to use the knowledge in the sigraph papers... But this avenue is useless unless you actualy know math.
Switch utilities are described in the manual pretty deep, altough the use for them gets blurry for many even tough it represents the base usage for them, still most users wont get it. Same goes with uv chooser, wich just chooses what uv to use for the texture.
But you are actualy missing the interesting nodes like ramp, placement and projection... that can do a whole lot of things i bet you havent tought of. Bothe of thema are the workhorses for poredural texturing.
And then there are all the other nodes wich can also be used, the combination of theese sums in a infinite array so its not possible to explain all.
