Are prices in the next 12 months going to be flat, increase 1%-5%, 6%-10%+ or decrease? 

Whe shopping around you are going to see that some charge more interest but less closing costs and other less interest and more closing costs.

My app lets me see the last week or on month level.

If your tenants start leaving at the end of every leasing cycle it will cost you dearly.

Or most lenders will say the gap from the last property you sold should be no more than 5 months!  

Would only need the loan for 6 months. 

I have an updated single family ranch home 4BR, 3ba ~3000 sq ft in suburb of Cincinnati, OH that is currently leased at $2700 per month.

Am I reading this correctly that I can not charge late fees that total more than 10% of the monthly rent even if I have a different amount in my lease and only own 3 rental properties in Virginia? 

Real Estate is definitely not just a "numbers analysis" and you are definitely thinking about things the right way - but I think a good next step for you would be to spend some time putting a lot of this stuff into a (very) basic financial model/spreadsheets mapping out all the potential costs and estimates on effect (effect on value, on exit, different scenarios) - I think getting started with that framework should help with these decisions immensely

The applicant makes 1900$ monthly and will be responsible for 689$ from the entire rent.