Yes.
Yes.
For anyone who thinks this is hyperbole, ProPublica has done excellent work investigating how lenders use the court system to imprison Americans who can't pay back their debts: https://www.google.com/search?q=propublica+debtors+prisons
Debtors prisons are bad but of course that’s a separate issue.
> Yes.
By this logic, slavery should be legal, because people should have the freedom to sell themselves into it (for instance, to purchase medical care for a loved one).
Huh? I literally said the person would be selling themselves into slavery, which means becoming chattel property with no rights of any kind. That's nothing like a non-slave "working for a predetermined rate," because those workers still have rights since they're not property.