Once established, this tree is known for its tolerance of drought, air pollution, and a wide range of soil types.

This would have been your first clue that there was water underneath. 

Also, keep an eye out for an oil tank... in my neck of the woods they are one of the biggest issues with old houses and can cost thousands of dollars if they have leaked and the soil needs remediation.

We owner-occupy, and our tenant put a fire pit (the metal bowl type from home depot, with just grass underneath) and a grill in the yard while we were away for the night.

The caulk prevents 'other' liquids from getting underneath, and I don't just mean when the floor is mopped; bad aim, overflows, drinking too much the night before, etc.

Women choose what house to buy.Tile's great in kitchens, halls, etc. but if you put it in a bathroom (especially at your $$ price point), you might consider adding radiant heating underneath.

I have no idea about soil conditions where you are or if the land is virgin or been previously developed.

Since soil conditions, grade, rainfall and runoff, etc vary so greally from locale to locale, you need someone from that area to consult. 

Some builders don't include fees for plans, renderings, soil samples, landscaping, etc.

Income averaging as it were.. as I lost roughly 5 million personal in the wipe out...now I am financing the new guys in Jackson ( call me crazy) but their exit is a refi to keep them I would never loan to another out of state investor in ANY MARKET in the US.. just way to risky and having been there done that.. so what did I learn owning 300 plus home sin Jackson .. long story short your correct this investor will have cap ex up the Yazoo but he does not know it.. the tenant class the soil conditions and the fact that these homes were built about as cheap as a home can be built in the day all lead to extensive cap ex. but that is MS... and Jackson in particular.. rent to purchase raitos are stellar but you need to stay on top of these homes.. if you let them slide one inch the next thing you know its a 10 K turn over