Charging about $375 for visual, moisture testing, thermal imaging and air or swab sampling in up to 4 areas.

Drywall sucks water so unless you have a moisture meter it can be hard or impossible to tell what is saturated. 

The basement had been clean and dry, but apparently encountered a moisture problem over the summer and now the back sides (all exposed particle board) of the cabinets are covered in green and white mold.

Temperature variation across the length of the planks is probably contributing, an inadequate moisture barrier underneath, the contractor didn't seal the ends of planks near the door, or maybe there's not enough of an expansion gap between the walls and the floating floor in that area. 

The moisture  collects there and rots the log.

Look for evidence of moisture on the ceiling, especially along corners and look for ice dams or evidence of ice dams (shingles will be torn/dented) 

But I'm having a hard time estimating the cost of repairs like uneven floor joists, drywall install/removal of plaster, moisture in basement, electric, plumbing,  etc. 

Below are some generalizations about ongoing maintenance costs: Older properties require more maintenance than newer properties.Composition roofs require more maintenance than tile 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 or stucco siding.Properties with lush vegetation require more maintenance than properties with little or no vegetation.Below is a typical Las Vegas single family class A home.In summary, I believe Las Vegas is not only a good place to invest today, it has a high probability of continuing to be a good investment location into the foreseeable future.

Use screws long enough to penetrate the oak and bite into the wood beneath.

If water is penetrating the house, mold will not be far behind.