Immigration is one issue, while business setup is another. You need legal help on both sides, ideally coordinated. Find someone in your area like us, who handles both immigration and business law. It will be more cost effective.
You would use an "escrow" company to handle the transaction. Money and ownership doesn't change hands, unless all the requirements are met, and some of these requirements can be payment of the debts. You can use a "real" escrow company, or an attorney acting as an escrow.
Courts will allow certain amount of leeway for unrepresented litigants, but in the end of the day, it is a complex system and having an attorney who knows their way gives a clear advantage that is hard to overcome, even if the facts are on your side.