For the downloadable part, shapeways already offers the 3D parts database. I don't know what the roadmap for that is, but I don't think it is far fetched to assume it will become boiler plate functionality for all uploaded models at some point.
There's just the little problem of keeping things simply and at the same time offering us a gazillion options about what other people can do with the model
(Model details page is already getting a bit longish what with all the current options)
texture/UV map download option for co-creators sounds good. But since co creators are kind of meant for the less 3D modelling technical inclined as far as I know, I am not too sure if it would be a big seller. Being an amateur 3D modeller myself I find UV maps to be quite daunting. The whole 3D mapped to a 2D plane just confused my brain I guess.
But the notion of being able to supply more instructions then just plain text would be a good thing I think. I could see for instance how some images could visually explain what certain co creator variables would influence. The negative side would of course be that it means more work for the creator. Food for thought, that's for sure.