My further research indicated that any deficit in return on original loan amount is considered a "non-business bad debt" treated as short-term capital loss, but foregone interest is excluded (because individuals operate on a cash basis). 

I will also indicate that due to this additional cost that we are going to have to defer  some improvements  due to this expense.

I simply warn people about shady turn key operators, which we both know exists in this industry.

Right now All of my real estate investments focus on investing in turn key properties and becoming a limited partner in syndications.

I completely agree: Running an ad does not place your property "in Service", which is the key point in time at which you can begin expensing your renovations rather than capitalizing them.In order to be "In Service", the house must be habitable.

What are some of the key factors to know and understand?

Fast forward, yesterday with A LOT of notice our hired realtor showed up at the house to get a key from my tenant for showings.  

Study the landlord tenant laws in the community you are buying and see how much notice you have to give your tenants before nonrenewal or look at cash for keys.

We have a pro membership, created a spreadsheet to learn the key metrics, have adequate resources and high credit score.

Why are you going turn key?