What does the Water supplier require to attach to their system.If water or soil ph does not affect copper it is the best and obviously most tested for durability and longevity in the interior or exterior.  

Could have pretty layer on top and all junk underneath in bad shape.

Off the top of my head, I would want to know about zoning, dividable, legal access, physical access, road agreements, easements, floodplains, utility access, wells, well agreements, setbacks, environmental issues, and soil tests.

In cold climates you want to make sure the deepened perimeter of the slab is below the frost line so the expansion of frozen soil doesn't heave the building up, but if it has been fine since the 50's you should be ok.

That area is directly underneath the upstairs guest bedroom and bathroom.

If it's near water, are there problems with flooding, soil erosion, insects, etc.? 

What I have found is that when you hire the right GC, you are getting all reliable subs underneath them.  

You won't know what you find until you pull the roof off and look at the decking.We have a commercial project right now for a 11,000 sq ft roof and 3 estimates it is about 45,000 but doesn't include if certain items are found.There was a larger section of the roof we took core samples on to check integrity underneath the new membrane that was added about 7 years ago.1,500 sq ft is  smaller job so I would think your quote will be higher than the larger jobs due to smaller overall profit.There are generally 2 warranties with one from the roofing company and one from the manufacturer. 

This type of movement indicates wall is being pushedin by soil pressure.

Inspecting everything, making sure things work, testing soil, etc.On the face of it, seems like an OK deal.