I would be a little cautious with your rehab as older houses can have a lot more hidden expenses, so just be conservative with your estimates, it sounds like it could have foundation problems if a floor is dipping.

This will also help determine what type of home you ultimately purchase and provide your beginning foundation.  

Now i know things like mold, plumbing or foundation issues sound scary, but is it something i should leverage and not be afraid of and fix or not dabble in that area?  

That is supposed to be the guiding foundation of "MERICA" is it not?

(mid and long term rentals) If I get 30 homes that get 3000 income a month (all my (4) currently do) then my goal is done and I can move forward with that firm financial foundation to do things that I really want to do in my personal life/non-profit space.

Shouldn't major foundation issues be something that should be reported in home inspection at purchase?

You don't need to know everything to get started; you need a foundation to build on and the rest will come through experience and then refining your education.You can build a basic understanding of investing in 3-6 months.

There's nothing wrong a slab foundation in fact they are more energy efficient typically. 

Financial Planning: Start building a solid financial foundation early.

In MHP's they are regulated like cars rather than real estate, but the renovation is mostly the same (sans foundation issues, and structural issues if leave the outside walls intact).