First time questions regarding lending money for fix and flip*

[Chad Herring]

I've decided to become a private money lender for a fix and flip investor. I've done my best to research the process but wanted to get additional guidance. I'd like to loan around $25k to start, but I'm undecided on loan terms, so any guidance in that area would be great. It seems like interest rates are most common, so that's what I'm leaning towards, but is the ball in my court regarding the terms or in the investor's? Additional questions are regarding the legal process: Do I need an attorney? Do I need to set up an LLC? 

*Reposted from another forum.