I would increase your CapEx and Maintenance expenses (I use 10% each for older, lower valued properties), but I err on the conservative side. 

” (35 ILCS 200/15-175) The amount of exemption is the increase in the current year’s equalized assessed value (EAV), above the 1977 EAV, up to a maximum of $7,000 in Cook County and $6,000 in all other counties.Our scenario is my mother and step dad live in a SFR of ours and their rent is solely based on the total costs of the property (mortgage, insurance, and property taxes).

I just increase my rents by $50 and say water is included, job done.

The price has increased quite a bit around 50%.  

The common saying you get what you pay for definitely justifies higher rent as my focus is to differentiate the properties with quality and customer service. 

Is there potential to use it for AirBnB or some other short term arrangement to increase the income?

There WILL be other deals.Your knowledge/experience WILL increase with time.There's no reason why your Flipping101education NEEDS to be expensive.ie.

Secondly, you will almost always get more bang (read: bigger rent increase) when you upgrade amenities (say new cabinets or flooring) between tenants.That said, in my books there are exceptions for long-term tenants.  

I shouldn't have said that it increases the cap by 1%, but just using that as an example to show how big of a difference it makes.This will double my # of units, so just want to make sure my numbers are tight.

IE, that the bill payment company really exists, then contact them with the number I find, not the one she gives me, find out if she's a customer, see the police reports on the identity theft, etc.