Newbie here - 2 weeks into my first property, I plan to house hack short-term rental (live in basement, rent main house) in Nashville.

Start in your backyard" is a common theme but doesn't work in every location.

or will your rent it out or sell it in the future. 

If you have a distressed investment property or a property you're looking to rehab before renting, a fix and flip loan product would be the right product for you.

I am in the midst of rehabbing my first deal (a rented triplex with long term tenants that was owned by a major slumlord). 

To be honest most of it is learning on the fly as each property, tenant, and location is different.

My dad broke up the concrete in just a few locations so water could seep through and drain into the soil, then filled the pool with the cheapest stone and clean soil locally available, then planted grass.

You got bad advice from your prior accountant.You received rental income and it should have been reported.it seems like maybe he was lazy and/or doesn't understand rental concepts.The only exception is if he is paying 'under-market' for rent in which case the property would be considered personal use.I would fix the issue and charge him market rent. 

Is the squatter some random person or where they living there at one point and stopped paying rent? 

I’m about to find houses to do wholesale, fix and flip or Rent with it, I would like to know who’s ready to get a contract assignment?