From what iv’e learnt about rigging, it is best to leave any unwrapping and texturing till afterwards as you may have to make topology changes as you rig to get better deformations which could then make any UV’s and texturing invalid and you will have to start again. I can’t remember if I linked this or not, but @danpro ‘s great series about using rigify will train you how to rig and weight a character efficiently for posing and animation. It has everything you need to know about rigify and weight painting in there and I thoroughly recommend anybody to take the time to go through it.
https://www.youtube.com/watch?v=uIZ-kCFASKE
As for the shrinkwraps, I’m not sure, it’s not something iv’e personally come across yet, but Dan may be able to help with that.
Also, I got your PM , ill get back to you when im back on my computer and can reply to it 🙂
