Hi, NightSkyTraveler, and welcome to TUG!
I hope you don't end up feeling too much like you're under a microscope here but as you already know, you're like a rare bird sighting in that you're the first DC Points resale owner to post. And boy do we have questions!
About what I bolded - that's interesting because it means that resold Points will transfer the same as in DVC (Disney Vacation Club) and retain the same Use Year as originally purchased, which makes for different reservation windows, banking/borrowing deadlines, etc. depending on which Points are being used.
Also, if someone owns Enrolled Weeks and purchases DC Points direct, the Use Year of those purchased Points is usually set to the same calendar-year Use Year as the Points from converted Weeks. But if purchased/transferred Points resales retain their original Use Year, which it appears in your situation they have, then it will be possible for Enrolled Owners to also be dealing with different Use Years.
I know DVC Owners try to tailor their resale purchases so that the contracts' Use Years will coincide best with their expected travel. It's definitely something to consider as the Marriott DC Points resale market develops.