not in DFW, but i was getting in the $3-$5 range and they were insured and had references. As far as staying power and whether they will be around in 10 years....who knows. but does it really matter. I doubt you would get more than a year warranty and if it is just a driveway I don't see a lot of risk there. Especially enough to pay double. Just my $0.02
Yes, reputable contractors that have been used many times. I'm pouring close to 5000 sq ft. Obviously, the price goes up for small jobs, but shouldn't be much more than 3.50 - 3.75 / Sq ft for a driveway.
Yes, concrete is priced by the cubic yard when you buy it, but 99% of driveways are somewhere between 3.5" (depth of 2x4) and 4.5" thick and the concrete contractors know that, so you can get pricing based on a square footage. Obviously if you want something more substantial, you'd have to specify that and it would be priced that way.