JV-ing and Loans – How Do You Structure? What Contracts to Use?

I am getting started with JV-ing on projects and builds now. For people who are familiar with this and assuming that financial split is 50/50 for the investment:

1. Do you typically form an LLC and have both people on the loan?
2. Is there ever an instance where you JV and do not form a LLC and only one of the partners is on the loan? What is the benefit of something like this?
3. What type of contract agreements do you have between your partners?
4. What are some of the key things to include in a JV-ing partnership?
5. Does anyone do investment partnerships where there's investors and a preferred return is provided? How does something like this work? Contracts?