I get an email with a picture when camera detects motion.I might be able to get a discount on my insurance for the security cameras but I haven't pursued that yet.

You might spend that, or more, just getting your license, keeping your errors & omissions insurance, paying office costs, etc. 

Which makes sense if you have three large apartment complexes, because they each represent a large sum of equity and risk exposure.Be sure you run a responsible business, maintain your properties well and make sure they are code compliant, get good insurance and an umbrella policy on top.

The lease doesn't terminate when someone new takes over.Having an umbrella insurance policy has zero bearing on managing property.

I am not large enough (16 SFRs) to self insure because I need some degree of coverage for catastrophic events. 

I want to start flipping houses but I’m curious about what I should in for insurance.

Property insurance is, and flood insurance may be, required.

These 2 should provide me close to $1,000/mo to cover her student loans after debt service, insurance, capex, opex, taxes, and vacancies.

This year they became unresponsive and I finally reached out to their insurance on the COI.

Remember that must PM companies hire licensed and insured people to do the job, but a handyman with no license or insurance that just came from the Day labor pool??!!!!!