Who am I actually buying from when a wholesaler 900 miles away holds the contract?

What you're buying is a contract position, nothing more. Strictly, an assignment transfers the wholesaler's rights and duties under his purchase agreement with the owner to you. You step into his shoes. You don't get better rights than he had, so if his agreement has a weak specific performance clause, a short inspection window, or an earnest money forfeiture term, all of that is now yours. The loose market usage where people call the whole activity "selling the house" is wrong and worth pushing back on in writing.

Before money moves, ask for the fully executed original purchase agreement with every addendum and any extensions, not a summary. Check three things in it: the closing deadline, whether it permits assignment at all, and who holds the earnest money already deposited. Some agreements prohibit assignment outright, which turns your $9,000 into a payment for something he can't deliver. Also get the title commitment in your name and confirm the escrow instructions directly with the title company using contact details you looked up yourself, not the ones in his email.

If the original seller refuses to perform you're the party with the claim, and your remedy is whatever that agreement gives you against a person you've never met in a state you don't live in. That is usually the practical end of it.

On the $9,000: whether it must appear on the settlement statement, and whether disclosure of the assignment to the seller is required, depends on the state, and several states have added specific wholesaling disclosure rules. Ask the title company how they intend to paper the fee and get the answer in writing. A closing attorney licensed in that state should read the assignment before you sign.

The part you haven't raised is the comp sheet. Roughly a dozen states don't make sale prices public, so his ARV may rest on listing prices or an automated estimate. Pay for an appraisal or a local broker's opinion at your own cost.