Having resources to get major things repaired same day in order to preserve a stay.

I don't currently own a home yet, so my thoughts were to buy a duplex and live in one side and rent out the other, or stay in my current rental while I set up other investment properties.

Vacancy is costly and while there is no way to guarantee one tenant is going to stay longer than another, talking to people and learning a little about their life and situation should give you some clues as to how long they might stay in your place.The probability of you getting a home-run tenant right off the bat is pretty low. 

In addition to what @William Simpson posted I would add the following platforms: - Roomies.com - Spareroom.com- Roomster.com Beware, as some of these are not free, but they can greatly complement the free ones already mentioned. 

I like to buy my appliances on sale with free delivery and hookup.

I am selling my 3 bedroom house right now...it had no pool and was not as close to the water, but stayed booked easily with smaller groups.   

Last time I spoke with him he wanted to be sure I was staying another year when my lease renews in July and promised to only raise rent $25, which he held true to.

Stick to your criteria and buy box and stay focused on what you want

If your tenant only stays 2 years each time -  you are permanently negatively cash flowing until you can change your financial situation.  

I shot you a colleague request and would love to stay in contact to see if I can help you going forward!