Routing development

I am looking to find a way to calculate and show over a single map the routing from

A to B
A to C
A to D
A to E


I also want to be able to do the following
I have 100 vehicles leaving site A and a % going to each destination ie
A to B 20%
A to C 40%
A to D 30%
A to E 10%

I want to be able to calculate how many turn at each junction.

Do you know how this can be done?

Sounds more like a question for Stackoverflow, to be honest.

… or a question for … ?