never admit to previously flying the aircraft.
never admit to anything.
before he leaves ask him pointblank 'are there any violations?" If he says no then you later take off he has no violatioon against you. he cannot mislead you.
every word you say can be used against you in a violation hearing. keep it shut!
do cooperate, if you are acting like a jerk and piss him off you will have problems.
to end the ramp check early, tell him you have to leave NOW, as you have a clearance void time (uncontrolled fileds only) and he cannot delay you.