

Yes it does. It’s a legal form of payment, and if a lender denies it, you can sue to have the entire debt discharged because the lender is refusing legal tender.
If you’re a debt holder, you’re required by federal law to accept any form of legal tender as payment, which includes coins.
Yes, you’re correct. That’s where the “debt” part comes in. If it’s before you incur the debt, they can refuse to accept any legal tender.