2 newbie questions
 

first Porsche. 1992 964 Carrera. some dumb quesitons:

what grade of gasoline should I use?

getting a 964 with 60k miles. should I do a 60k mike "check-up"? what are the major things I should have checked?

Premium

If it has not had it's 60k service, you should have it done. It's a "major" service with plugs changed (a real PITA), valves adjusted, etc in addition to an oil change.

Did you have a PPI done before purchase? Did you get service records from the seller? If you answer no to both questions, you should make sure you get it to a good Porsche shop and have it get a thorough service and inspection.