The current owner purchased the property with the intention of opening a little health food store but never got around to it.

Good, because that mental image is about as close as you'll ever be to getting your back rent.Just get rid of the tenant, put him into collections if that makes you feel better (don't hold your breath on collecting anything), and learn your lesson.

As you ask questions, you also want to make a judgement (mentally) on the response you are hearing.

Landlords are required by law to provide proper living conditions for their tenants, free from health or safety hazards, often referred to as an "implied warranty of habitability."

If the numbers work and you've already mentally prepared for chance of future floods, keep pushing forward.

Cmon guys, it’s so common to have this type of turnover during these years and medical (including mental health) things often come up with young adults.

He lost his job due to health reasons and has been receiving treatment from the VA with him being a Vet.

Leverage is fine and dandy (especially when others pay it for you), but you need to mentally walk-through all scenarios and ensure you have an answer for all angles of Murphy's Law. 

And thinking of building of a portfolio rather than simply owning a single property at all times is a newer mentality for us, but I think one that would ultimately pay off more in the long run. 

However, it'll benefit you to work on getting past that mental block.