I was trying to buy and hold it and offered 75k, figuring a rehab budget of around 25K if I added a duct work and new HVAC system (heater/air conditioner), some normal drywall laminating, floor refinishing, and exterior rehab.

What can I do to prevent my self from unforeseen surprises?

No ductwork to waste hot/cold air.There are tons of options available and this is just one I plucked out of thin air.

Process was quick and they did an air appraisal. 10-14 seems way too high for a heloc

Going to use FHA as I plan to either live-in flip, air bnb, or house hack to live for free as I will be working as a night shift nurse in the KC, MO area.

A DIY mentality would dictate that you purchase repair books from Autozone, watch hours upon hours of Youtube videos, buy tools you need but don't have, and probably still throw your hands up in the air and have it towed to a garage because it's overwhelming.A tax return on the other hand is like the tip of an iceberg. 

LLCs also prevent Sue Happy Sam from taking your personal belongings and accounts.

In general, courts are allowed to pierce the corporate veil to prevent fraud or grave injustice.

Dead air from his side so far). 

I have to wait a year to up their rents, then I’ll be able to add a few small things like air conditioning, new sink.