Essentially, if no new properties were listed, how long would it take to work off existing inventory. 6 months would be balanced.

However, it’s essential to understand: even strong real estate markets have bad investments.   3 Signs Kansas City Looks Like a Strong Real Estate Market:1.

I would like to make a prepayment, however I do not want to decrease the duration of the loan, instead I want the loan to essentially recalculate thus reducing my monthly payments because I've paid down some of the principal.

Lastly you need to ensure you have the essentials in place before you start. 

Do not start up an electric water heater until it is filled or you will burn up the elements.

Also in the case of a lawsuit, a one person LLC might be considered to essentially just be you and then you could be personally on the hook for a ruling against the LLC.

I know that filling the cavities where the iron weights are moving around with insulation (closed cell foam preferably) is essential.

However if your main income comes from real estate, essentially making you a real estate professional, then you would file Schedule C and your rental holdings are no longer considered a "passive" or "side job", but your primary income, and subject to self-employment tax.If you are unaware, self-employment tax is the portion of employment tax an employer pays on your behalf, up and above what they pay you in wages.

By effectively eliminating investor owners, they are reducing the pool of potential buyers and essentially lowering values. 

There are essentially only two that are used on a widespread basis: PropertyInsight (Fidelity's), and DataTrace (First American's).