The man had a restraining order placed against him from the woman, he came back to the house, and the police arrested him.

You should be filing a police report.

Tenant took photos and filed a police report, suspect was arrested as well. 

But for an interior of the house where you as the owner reside while renting out to roommates ("house hacking") - is there a camera or system anyone can recommend for:1) Monitoring guests brought over by roommates in the common areas (my friend has a guest policy and cameras would obviously help ensure the policy is adhered to)2) Potentially helping police identify someone should they break into the house?

All polices are NOT created equal, make sure you get a good referral. 

The tenant needs to seek police help.

Next time they call, ask them to call right back on your office line, and give them your lawyers number or police station. 

I had a similar issue with my other property about garbage cans that lead to the police being called.

Too bad the public cannot police the city/county if they own the property (like you mentioned) and leave it abandoned and sitting.

No pet polices are not followed and a dog as chewed on some nice 100 year old vintage woodwork.