However, assuming you would be permitted to merged the lots, the cost of merging and the negative implications when it comes time to divest may outweigh any reduction in property tax.

If I buy property with a rehab required it is the day I close the permit or get the U&O. 

Ran across this nice summary of each city in the greater Cleveland area regarding Point of Sale, Occupancy Permits, Inspections, etc.

If things went south with the SO, would I have any extra rights to the ownership of the house if I am able to show proof that I have been the "breadwinner" and paying for the house mostly on my own?

The cost of HML is much higher than the “extra tax” you pay.

Tonight is a holiday but I will review all the details of our Florida real estate contracts as I know there is a section that discusses cooperation from seller with closing out of permits, liens, etc

When opening a boarding home, the city requires you to attain a permit.

If you can swing the extra payments due to the shorter repayment period this may be a much better way to go.

And it will allow me to earn extra income to help purchase more investment properties. 

Permits, utilities cut off , estimates .