Assuming we keep the property until October 2020 we'd see a 9% return on putting down 10k or so to reach 78% LTV and remove PMI. 

Therefore, you double your money (assuming you can still sell the property with a 2% CoC return, of course) in 3 years. 

On 7/28/18 I got a letter from her stating she was not returning my security deposit of $2,100 due to repairs the apt required.

Being in and out of houses all day, every day give you insight on market conditions and allows you to take a pretty solid guess at ARV before you even run the numbers.We still suffer some of the regular problems though - like finding contractors who will show up on time and stay on budget.I have contacted about a half dozen paving contractors to look at a job at my home.  4 never returned the calls, two showed up and promised estimates. 

They are paid a return (and eventually their principal back) via cash flow and/or from the sales proceeds when the property is sold. 

Will she be able to return to NYC to complete the search?

Your returns on invested cash are lower as well.  

I have EXCELLENT credit (almost 800) and am a business owner that showing a nice income on my tax returns.

I'm thinking about putting the money somewhere 'safe'(maybe something like us treasury money market fund) that would give me enough returns to match inflation, so that i could then invest that when there is a downturn/correction/recession, without losing any of my buying power.

You'll start getting the returns you're looking for...some money, education, and experience with less risk.