Business paying back debt to individuals

I have a single member LLC (Missouri, United States) that I started a few years ago. We received approximately $20,000 in funding from family and friends, of which I did not fully understand the implications of at the time that it was done. It was never declared as any form of "investment" and did not grant any ownership of the company. It was money that was simply borrowed from people around us.

We are now at the point to be able to start paying back this money to the individuals. My question(s) now is the best way to pay them back.

1. If we pay back exactly what was paid in, will we need to record these payments as income for the individuals (W9s) to where they have to pay taxes on it?
2. We also plan on paying recurring percentages of business profits to these individuals after the initial amount is paid back, so what would be the implications and requirements to do that as well?
3. Would payments to these individuals (either type) be an expense for the business to write off, or would they be taxed for us as well?

Finding the answers to these has been a little difficult since these were all personal friends/family, not banks or venture capitalists.