I am also very concerned with environmental factors inside the home due to the known water damage.

Was there anything particularly unusual about the deal such as a phase 2 environmental etc?.

I usually give the seller 7 business days to provide items.1.Any Permits and Licenses2.Certificates of Occupancy3.Existing Surveys or Environmental Reports4.

Take a look at the footprint of the FrontRunner. 

I would be completing Phase I Environmental Site Assessments as required by the lenders, and also mold, lead, radon, and asbestos testing as other service options.

Where would you think is the best state to invest for longevity/safety/limited environmental issues like flooding, tornadoes, extreme heat etc aren't a problem?

We have a large footprint in SD and would love to assist you in any way we can. 

Finding out city zoning for new construction on this property, finding out about environmental impact, speaking with the development head in the county, also getting information on the water sewage and electric for the property and what it’s connected to.I offered one of the investors, let’s do the flip.

It sounds from your description that a SFR here was converted into a four-plex, meaning that the entire four-plex sits within the original footprint of the house and there were no unpermitted additions. 

If that's the case, you can't do any renovations until you have it professionally deleaded or it would be flagged for Unauthorized Deleading and you can get fined and the property would never be able to get a Lead Certificate, only a letter of Environmental Protection that states you did illegal work, got caught, then had to pay a professional to clean up the mess.