The creditor sets the minimum payment. If this an arrangement you made with the creditor you should be fine as long as you keep paying. If you just arbitrarly decided you will pay 10.00 a month they may send it to a collection agency
There is no minimum required. That applies to credit cards, not medical bills. If you do not have a written agreement, then you are at the mercy of the creditor to not report and not turn it over to collections. Get everything in writing.
[This communication is intended as general information and not specific legal advice, and this communication does not create an attorney-client relationship.]