Can I look at flight logs and battery charges etc?
yes if the current user is with you it would all be on the device he uses.
or if they use healthy drones they could share the flights with you and much of that is shown there.
when I have sold mine ,
I would fly it for/with the buyer ,
show him all the basics of flight and how to calibrate compass etc.
show them video of the flight we just had etc.
never a callback or complaint and have used and resold 5 phantoms.