I'm being threatened with lawsuit by Junk Debt Buyer/Law Firm who paid pennies on the dollar for the right to collect my credit card debt in Ohio. They've also added almost $7000 in fees to the amount claimed due. Can I discover what amount they paid for the debt? Can I file a motion to reduce their claim to the amount paid for the debt since that is the extent of their injury?

No you can't file for a reduction based on that reason. And no your not entitled to know what they paid for the account. They did suffer more damages as there is an expense in pursuing you in court. All of that is in your original contract. Your other option is to ask for some type of settlement and keep to it.