No answers to any of your questions, sorry but hubby is wanting to do this with our coop. He googled solar panels and seems convinced he can do them. Maybe a google search would help you?
It seems the biggest question is: what do you want to power?
If it's just some lights, use LED's and you can get away with a very small system.
If you want to run heaters, a big stereo and a disco ball you'll need more.
What are you trying to do??? Solar panels for heat? light? automatic door?? Personally, I couldn't see why you would need any kind of power for a chicken coop. Keep it simple