You wrote “and we had negotiated what they were going to get for helping me.” So this makes it appear they were not doing you a favor. If they...

Confirm, first it is legitimate. Give no information but have them provide proof.

If it is not a verified complaint, yes. Consider what affirmative defenses to include and if a cross complaint or a motion should be filed.

Consult with experienced debt collection defense attorneys in the state where this occurred.

It is unclear what occurred. It appears it may be the bank at fault. Consult with experienced attorneys in the state where this occurred.

The attorney cannot provide those documents to anyone without your permission.

Yes you can outside of court. But be aware there are many family dynamic matters that may warrant using an outside party.

It depends on the fee agreement and what was done.

It depends on what they are doing and for whom they are doing it.

Losing a case does not warrant a refund. The questions are did he do the work and did he breach the standards of care.