I love the idea. Hell, I could use a loan. But I highly recommend reading Hive account@kevinwong's The Honesty Post. He touches on accountability, trust, having a contract.

Repayment amount should not be determined by the lendee. I would implement interest. You borrow 100, you pay back 110. I'm not suggesting 10% but I am suggesting something.

I would also recommend payback options: % Steem per post or a specific time frame. And people need to know what the consequences are to defaulting because taking the money and running is not fair to the the other lendees or the investors.