As for the Florida property, as other s have said, its a personal preference. 

3-year PPPs are usually reasonably priced while also shaving off those extra 2 years...if you drop below 3, rate/cost can get a little gross.

Those in their 20's , 30's and even 40's have a hard time with housing expenses .

We sealed the holes with spray foam and wiped vanity down with a bleach solution on Nov 21st. 

The build cost would be a little higher because i would use foam in the exterior walls and also use insulation in the interior walls for energy saving and sound dampining.

If youre still not able to qualify, work with your lender to see where you can shave out some monthly expenses.

.$24.99 Zinus 1.5" memory foam topper Queen size - https://www.amazon.com/Cooling-Mattress-Airflow-CertiPUR-US-...We have these in our rental and they have been great.

One of the closets has this hideuos foam column. 

I like number 1 just based on what I read, especially if you can get a new primary and shave off a downpayment for an investment property.

If I were to put 2400 per year back towards the mortgage, the 6.375% equates to only (maybe) 150 per year that I am "making", but if you do that for a few years up front you can shave off years on the back end of the mortgage.