Idea : Implementing a way to ordonnate nodes

I want, in a site, to add relationships between nodes with a taxonomy vocabulary.

For exemple i add a vocabulary "branches" with 1.x, 2.x, 3.x term. Then i create some page for documentation : introduction, usage, etc.

I want to display a block in my page with the related pages, for exemple when i'm on introduction for the 1.X branches, i would like to add a link to introduction of the 2.x and 3.x branches. Maybe node relationships can do that.

Now, when my user try to join my website with a direct url like this http://www.site.com/2.x/introduction, i want to serve him the page or a related page. For exemple, if i didn't create the 2.x Introduction, he will be redirect to 1.x/introduction.

Do u know some module that can do that? If not, i can try to develop this module.

Thanks.