If you assign the contract then your end investor is responsibe for all obligation of the contract including setting up a closing.
Yes, I have done almost every deal with just a title company, who else do you need? The title agents should be able to answer any of your questions
Im from michigan and I know you dont need an attorney here, and assignment form is so basic a 4th grader could do it. It may be in your best interest to have the form notarized.