I have found some excellant educational material on this site:
http://www.concretenetwork.com/
If the cracks are hairline width then they are likely only shrinkage. If they are in the floor and wider at the top then the bottom, then it may be "curling" which is when the top of...
I found some good information on thickened slabs just by searching on Google for "Thickened concrete slab" there are links to several building departments. It seems to be a common item for building departments to decide whether they will approve this detail. It seems prudent to not...
The slab in my basement is very flat. After a few water spills, I would have rather pitched it to the trench drain around the perimeter of the slab, maybe 0.5%. Flat may not be the most desireable.
