Great advice. I wish I had some of this prior to going in on a business venture with a good friend of mine. The biggest problem we faced was that my partner had just gotten into a relationship which requires almost as much time as a new venture. So while I was envisioning 10 hour work days, he was envisioning days filled with several breaks to catch up with his girlfriend and/or his work hours were based around her schedule. This made it extremely hard for me to focus and set time for us to work together.

With that said, I would add to the list of questions - What other outside relationships will you need to spend significant time on and how will this affect our work days/schedule?