winch questions

Hi,
I’m new to RZR and new to this forum. I have a 2015 900 EPS Trail, just bought new.
I have been told that a winch is good to have. I have a few questions so I will ask them all here at once:
What size winch do I need?
What is a good brand that is less expensive than the Polaris/Warn? I’m in Canada so less choices. Champion and SuperWinch seem to be the most available here.
What size wire do I need to run from the battery to feed it?
Wouldn’t it make sense to have the winch mounted on the back? Then you could get back to where you were before you got stuck.

Thank’s for any advice.
Jeff