As for me, if I were back to square one, knowing what I now know, I would instantly spend the money again for the program we invested in. 

-- Roommates could accelerate your savings and give you experience dealing with tenants.How are you going to handle two mortgage payments while your rental sits vacant for a few months - or do you naively think everything rents instantly?

Your downpayment would be instant equity and your consistent cash flow would lead to equity over time.

The clear and obvious answer would be to instantly pay the back taxes and offer a small lump sum for them to move with and just lowball in whatever structure works for the both of you weather that is a better sale price or a greater monthly payment to them and just find your middle ground that works out for you both.

The value of that place would go up $100K instantly with the new look.- Cabinets look good but I'd get rid of all the clutter above.- Take all the cheap prints off the walls. 

I'd look at doing an FHA 203k or a homestyle renovation loan to add some instant equity on your next purchase!

In 4 months….Honestly, best case scenario is you are turning your money instantly and you will then end up making 30k/year.

Instant equity gains after the build is complete, easy to manage, high demands. 

I can confidently say that these "master classes" and courses claiming to grant you instant success are mostly deceptive.

You're literally forcing instant gratification when you're at the 20 yard line.