This does not have direct answers to what you want, but he explains some nodes like object location.
Also shows how to make gradient in mesh space. You could make gradient (from Z position) then use lerp with texture for various strength.
Also there was some clever material function (random done entirely in material) that derp aii hineted me to create. I just need to find it. And since it is in material it does not need any blueprints input. You can seed that random with mesh location.
search actually found it (scroll down i made pic with that function).