The website states open 24 hrs, but is there a staff member to actually check in and inspect the car after hours, like 4 AM. Someone that provides a receipt. If not, what are the instructions of returning a car around this time early in the morning.

I left without check in. Don't have receipt. Got charged for $29. Called and resolved issues. Lessons learned: make sure to have receipt and inspection.

Yes, Orlando is 24 hours, there was a full staff there at 2 am when I was there

There is 24/7 staff on site, you just roll in and drop it off and leave, a very pleasant man helped me with my bags.