It still prints in layers, it's just printing the entire layer simultaneously, using projected UV light, rather than running a flattened tube of material over the entire surface.
Not really*. It doesn't create layers in a step-wise fashion; there isn't a cure -> step -> cure -> step sequence. The piece is continuously moved, with curing taking place continuously over the region of the structure above the oxygen "dead zone", eliminating distinct layers. The resulting continuous structure lacks the weak interface regions generated by other 3D printing methods.
*Of course, the 3D modeler must make slices of some finite thickness; but for this process these can be arbitrarily thin. Cure rate is the limiting factor here, not the number of slices.