If so, how much is the typical % rate charged on a such a transaction?

@Patrick Boutin, it doesn't appear that your agent structured a lease and option transaction.  

All terms for this type of transaction are fully negotiable between buyer and seller. 

My question is, should a memorandum be filed for all real estate transactions?

None of the parties to the transactions should hold funds.

@Justin Tortorich,The laws governing a property / transaction will be those of the state where the property is located, not the entity.

The lender is likely to insist it get listed on the MLS for full exposure to the market, and then the sale might still be subject to bank approval - which can also take months to get, even after the house is under contract.I recently had a similar transaction.

A win-win seller financed transaction depends a lot on the seller's motivation and circumstances.  

,So I've got this running document called "references" that contains the names & phone numbers of agents, and property addresses, of transactions closed in the last six months.Probably fewer than five percent of listing agents ever call my phone number that I put right there on that preapproval letter, to give me an opportunity to share it with them. 

Hey @Eric Moe I am a transactional attorney in Northern Colorado and new to BiggerPockets as well.