Is there any rental payment app that is just as convenient to use for both the landlord and tenant?

Try the Roomster app as well.

I currently have one of my rental properties set up as a fixed price rent with utilities included (I know, crazy, but it's still cash flowing $1,000+ at least every month) and I was curious to know (a) what is the ratio of people who include vs exclude utilities and (b) what are some good tools, apps, etc that people use to track monthly cash flow?

Any platforms that allows to keep track to have this at my fingertips in an app that isn't an Excel spreadsheet?

Apps such as AirDNA, Your Porter, Google Suite, Zapier, when utilized together can effectively handle the 75% leaving you to simply take up 25%. 

What technology/apps/systems have you used to decrease the amount of time spent on managing a similar properties?

If we get pre-approved with a national mortgage lender like Quicken, can the same app/credit inquiry be applied to multiple states. 

@Logan Jones based on using apps that my realtor uses it shows estimate of how much I would need based on the purchase price and other expenses.

I don't think you need an app with a monthly subscription to track property addresses of vacant houses if you are budget conscious and haven't done a deal yet. 

We're planning to roll-in a custom mobile app for the building to give tenants control of their own smart devices while allowing management to easily reset permissions and remove access on tenant move-out.Have you ever tinkered with Tuya smart devices?