The skill tree is not that confusing.
Basically you have a few active skills that you can use at a time.
And on each section have multiple skills to choose from.
Runes on each skill help to improve that particular skill.
Basically you want to choose which skills you like the most to be your active skills and which runes to help improve them

I dont know about +stats but if youre good with hunting and salvaging you can always craft again and again Xd
But that probably will take you much much longer time.
Or get the yellow weapons