Carpet and pad can cover some of the cracking and sloping that may be underneath. 

In addition, the longhorn state is famous is known for very sandy soils, hence the reason basements are rare (because the soils being so sandy, do not have the support like many other soil types which are more rigid providing force so the wall does not buckle. 

@Mohamad SuleimanTwo things concern me in the thread above:Foundations in North Texas are always an issue because we have expansive soil. 

Sounds rural... in addition to the septic report, I would get a soils report.

I looked underneath the spout there seems to be an opening under there.

Rental grade cosmetic rehab- paint, carpet to go, hardwood underneath so polishing ,  install window/central AC and/or fencing depends on the rehab budget. roof, windows appears new. furnace, hot water heater in good condition, no fencing or central AC, basement and foundation in good condition (little moisture there though) waiting on contractor rehab estimate.Rent range - $695-750 . $750 if install central AC and fencing.

2) when filling out the contact, do I feel 2 of them out one for me  and one for seller or do I just put carbon paper underneath the original and give him the yellow copy?

One of the occupied ones is wall to wall boxes, so it makes it hard to really know what is underneath.

Soils test?

You would be better off adding 2 vapor barriers - one in the basement and one underneath the flooring you are about to install - than trying to mess with filling the gaps with foam sealant.The right way to do this would be as mentioned above - remove the upper floor, drop a new plywood/OSB subfloor on top, and then install your vapor barrier and new flooring.