You're on the right track:
1) What regular service have you (or a shop) perform?
2) What service interval do you follow?
3) Receipts are nice but so many don't..
4) What modifications have been made, if any?
5) When were they made?
6) Who made them?
7) What parts were used?

What repairs have been made outside of regular maintenance? For example, failed EGR/FCV..., control arms, injectors, etc.
This will get you a good picture of what's been done, what's not been done and possibly needing (or about to) attention.. etc.
If it's anywhere near 100k miles, or more, the timing belt is an absolute necessity (for example).
Fumoto valve on the oil drain is a strongly recommended item. If/when the factory oil drain strips, permanent engine damage is typically well under way before you can pull over and shut off the engine. Literally, if it runs out of oil you have time to put it in neutral and turn off the engine before it fails.
Mark