Do colleges look at your full personal high school record or just at academics and extracurricular activities?
They look at whatever is on the transcript your HS sends. There is no standard transcript format, so if you want to know what yours say, ask your GC.
Aside form the transcript, they look at everything that’s included on the application.
In school, there was this thing called a permanent record. We lived in fear. Think about what troubling may be found in you personal record. If there was a problem, think about your response if something bad comes out. Be careful about feeling the need to confess. Instead answer honestly and completely.
News flash - the nuns lied about that. 
Are you concerned about disciplinary actions? If so, talk to your GC about your concerns. If you were busted for cheating or something like that, you will need to address this, but if you just got a bunch of dress code violations or were caught using bad language (usually only a problem at a private school), it’s not as big a deal.
Schools vary in what they send to colleges. Talk to your guidance counselor about what is on the transcript sent to colleges as well as any other specific concerns you might have.