It’s becoming increasingly frustrating—the seller refuses to provide any proper documentation.

. - So, recommend having that first hire document the crap out of what you want them to do.

Are these the only items we need to document?

They worked with me and had no issues explaining the steps and documents they needed from me.

If so what documents were used?

This is a document the Landlord must sign in front of a notary, by which the landlord is swearing that he property delivered or "served" the Tenant.

All our data was well-organized and cleanly presented (no dropping off boxes of unorganized documents in their lap).  

https://www.portland.gov/phb/rental-services/documents/tenan... 

No doubt; both of my neighbors at my vacation house got "free" roofs from guys who roam around after any storm and document that whatever storm damaged their roof - despite the fact they both had 15+ year old 3 tab asphalt shingles in the central Florida sun. 

Document the condition of the property thoroughly before they leave, and remind them that their security deposit hinges on the place being left in good condition.