Can we tweak pathfinding with weights?

Tl;dr: I want a "fewer traffic lights, more dedicated bike paths" option.

I know enough about programming and math to assume there's some form of (weighted) graph underlying the routing function (is this straight up openstreetmaps or some conversion in between?), in which case it's not stupid to assume this can be done IF the info is in openstreetmaps.

So what I'd like is (pointers to where I'm likely to find the info are also appreciated) :

• what information is available in openstreetmaps that would be helpful for this?
• how does this info get into CoMaps?
• how is this info used in the routing?
• is this a feature other people want and/or does CoMaps accept contributions in code (if it seems feasible)?

Thanks in advance!