Take a look at your contract. There may be something in there about the settling and cracking of the foundation. I know its almost impossible to guarantee a 100% crack free concrete foundation. Earth moves,especially in the colder climates.
Now for a few questions:
When was the basement completed?
Are the walls solid poured concrete or cinder block?(block walls are more likely to crack than solid concrete)
Was any back fill brought in prior to the foundations construction?(If the fill wasnt compacted and tested for compaction,this may be a factor)
Were the foundation inspected by the proper "authorities" before hand?
And one final question..did the crack occur before or after the house was built? My guess would be after.
Take a few pics of the crack for documentation.
As far as those 2 foot by 4 foot rectangles goes,IMO it was from pieces of plywood that the finishers used to kneel on while finishing the concrete. Are these spots easily seen? If there is a real indentation in the concrete,and you are going with some sort of floor covering in the future,then they can be easily filled in.
Finishing concrete flat is an art. My son does it with ease,but I ve attempted it and I ll leave it for the people with the knack.
I do lots of footing and concrete wall forming for different larger companies doing work for paper mills,iron mines, right now I m at a gaming casino. There was not inspector 1 on this job. Absolutley nothing was inspected. Not one footing, not one wall,tho they did take compaciton tests and took concrete samples for tension testing. I m sure,considering where you live,the proper permits/inspections were carried out.
I hope this gives you a bit of insight.