Do they assist with writing them and should we refer to one or is this something we could come to terms on our own and sign it and be done?

The 10% guarantee, is to make sure you get something worthwhile back. 

Has anyone ever dealt with something like this?

First, if something goes wrong at one of his other properties, a judgment creditor can attach the judgment to your property because your partner is holding the property (or his portion of it) through his LLC.

We obviously need to keep it economical, but I would like to do something creative, and I'm bored with our past designs (generally they consist of a larger field tile with horizontal accent stripe).

If you have a $100k property without debt and then pull out $75k by taking on a loan, then when you go to sell that property (assuming no change in value) then you would need to spend the $25k of equity and buy something for at least $100k - for most investors this is achieved by taking on equal or greater debt.    

You want to do something creative and look it doesn't hurt to ask, but you've answered it yourself.

I'd love to discuss some things with you.

Because Athens is a college town and I myself am less than a year out of college, I think this is something that I could make work as well. 

I'm curious to here the response on this because I am looking to try and find a property that I might be able to owner finance but I'm not sure if I want to pay a higher rate to that person long term if I can get something lower at a bank.ThanksTJ