These people were tenants from hell: they broke doors, punched holes in the walls, soiled brand new carpets, etc.

After purchasing land to build a home on, it usually takes a few months to do surveying, site and soil evaluation for foundation/septic/well (if necessary), and other paperwork.  

It could be a simple as jacking up the overhang with some temporary shoring and bottle jacks to replace the 6x6s or it could be as complicated as an under-designed foundation or soils issue.

Run away - most are considered hazmat sites and once on the map they are considered that to the EPA has confirmed that all contaminated soil & building materials have been removed and in a hazmat landfill -- you can only use a licensed contractor - it will big $$$$$$$ - property will be on top of the building & fire departments watch list

You have to till the soil, fertilize it, plant the seeds and water them before you can pick the harvest.

The bathroom is carpeted, so I am unsure of what's going on underneath.

I'm just leery of what is underneath all that rock!

I obviously don't want an unhappy tenant living underneath me, but they already rejected the offer.

I am not a contractor so I don't even touch a house this old (and very rarely run into one this old in the Dallas area),,,that is the type of house you start to fix one thing, only to discover 3 other problems....I know in some parts of the country houses this old are 'normal',,,,they aren't in Texas,,heck after 100 years and the way the soil moves it probable needs to change it's address

It depends on what you intend to do with the property, access underneath and how handy you are as to what you can do.