The presoak softens the ground and helps prevent runoff allowing moisture to get to roots. 3.

Upon inspection we found a brown /damaged ceiling, the appliances have turned from white to yellow, the smell has penetrated everything, and it's all very old (bathroom fixtures, carpet, etc.) and needs replaced anyway. 2) Basement - smells awful (mold?) 

Older properties require more maintenance than newer properties.Composition roofs require more maintenance than tile or metal roofs.Properties in climates with hard freezes require more maintenance than properties in milder climates.Properties in locations with a lot of moisture require more maintenance than properties in dryer climates.Wood siding requires more maintenance than aluminum, vinyl or stucco siding.Properties with lush vegetation require more maintenance than properties with little or no vegetation.Investment Team - Lastly, do not forget about an investment team.

We recently ran into an issue where the floor joists in the house were rotting due to moisture issues under the house where there was no moisture barrier from the ground and the house being built so close to the ground.

Mold is everywhere and requires two things to grow: moisture and a food source (soap, dust, etc).

I'm in central Indiana and moisture is an issue, but the current owner is putting in a moisture barrier.

To my knowledge, latex tends to bubble and absorb moisture which will only worsen your rust.

The structural issues are really concerning to me, as well as the moisture in the basement.What is reasonable to expect from the seller? 

Due to poor ventilation moisture has accumulated in the joists/purlins.

The manufacturer suggested a plastic sheet moisture barrier between the wood and the new floor.