Comment by mjevans

There should be reasonable standard terms for widely used contracts. Unit transfer of ownership / sale, rental of the same, etc.

The standard contract should reference that current framework of agreement, and fill in only the variables that matter, possibly with an appendix of penalty fees if applicable. (E.G. like https://www.gsa.gov/travel/plan-book/per-diem-rates has a cost metric for meals and room rates for each given area; notably this list of fees MUST be from a 3rd party or government source. It must be common use.)

A list of expected payments (quantity and date), transfer events, etc, as well as a summary for anything remotely complex. It should nominally fit on one single sheet of standard paper (letter or A4).

An itemized bill of incidentals E.G. for room charges / etc would be a different type of expense, that would be an add on of additional services.