Well, if they are fully functional on a slab with plumbing, HVAC and electricity, then they are a real asset with value.

Once you have a short list, get an account with each one and run them through the wringer to see how they really function.

I feel like $80k-100k is the cost we were coming to when we considered rebuilding the existing stairwell to the basement to a more functional one along with rehabbing the current rec room to an insulated space.

You are searching for a place to live, that is the primary function. 

If you do purchase a property with a septic tank, you can have it inspected and pumped so you have a baseline that it is functioning correctly if the seller cannot give you any history on it. 

Use search function this has been asked and answered many times.

I am planning to move into a property manager function in upstate New York.

I mean you can do it but its still not legal if you have a website advertising properties you don't own.. that's the key.. no advertising properties you don't own.. in any form or function.. 

The concrete slab that functions as a porch or kind of front door space also has a large crack down the middle of it.

The LLC, in my case, functions as a liability protection mechanism.You might be able to get some tax benefits from operating as a corporation (S or C).