Arrive early, be clean cut, look like a coach would want him to look if dating the coach's daughter, 100% of the time use "yes sir" and "no sir", wear the hat and uniform correctly, hustle everywhere, assume somebody is always watching. They'll gun the first few throws so be good and loose and throw fastballs early. 60 time won't much matter if he's truly a pitcher only, but the effort shows attitude.
Parents should be seen and not heard.
Not sure about "sponsorship"; my two are both in college ball now, one graduating this year. My last showcase was 3 years ago. They did 8-9 showcases between them and the only sponsor was my wallet.
It's good to do some showcases "early" so he'll know what to expect when he gets to some later that might be more critical to recruiting efforts.
Enjoy the ride!