So he took the electric bill, the water bill, and the sewer bill each month and divided them by 15.

Flat roofs, old roof age, old electrical, cast iron plumbing and non impact openings will mean much higher premiums. 

Obviously they require electrical near by.

I also pay for utilities for two units since they are not on separate meters.My additional question is: can I/should I raise the rents the $75-100 I would like to, ask for a pet rent, possibly ask for a pet deposit, and then also charge a flat fee for utilities for the 2 units I pay electric and gas for?

We added value by installing new HVAC, roof, electrical, & much more!

Also had a new front patio built a few years ago along with all new electricity a few years back.

I had squirrels get up into the attack two separate times and chew electrical wires causing the power to go out..a day before Thanksgiving one time.

A waste of time and energy - I have zero interest in competing with the Amazon of vacation rental search sites.Now I will state this:  If Airbnb was my only option, I would probably just close shop and focus on my other ventures.

While you may receive numerous inquiries from individuals casually browsing listings, focus your time and energy on serious prospects.

A permit had to be pulled for electrical, plumbing, and an egress window has to be installed in a bedroom.Honestly, I would just keep renting it out as is and not waste the money or resources on trying to convert it