We are thinking about investing in real-estate property run by our friend. She is looking to get investors on the endeavor. She will give us a promissory note detailing the terms of the investment and the returns. I'd like to know if the promissory note is a legally binding document. Also, does it need to be notarized to make it binding? Our names will not be in the title of the property. Can you let me know what other information or process I need to do to protect ourselves?