AE's camera is perfect. No distortion, DOF based on the math for a perfect lens. if you are having DOF issues then you either don't completely understand how all of that works or you are making some inaccurate calculations or assumptions.
Show us a screenshot of the problem with the modified properties of the layers that are giving you problems revealed. Just press the U key twice, PrintScreen and Paste to the forum or drag a screenshot to the reply field.
You have created a very weird extremely large camera. It's the equivalent of a 5 X 7 view camera with a 100 MM lens. That's an awfully odd combination. Your aperture is extremely wide for that kind of a camera setup. In the real world, it would be extremely difficult to focus. I think AE's camera is having problems because you are so far out of bounds.
I would start by choosing one of the default cameras. If you really need an 80º angle of view a 20mm lens is about right.
The Ray-traced rendering engine is also awfully funky when it comes to rendering lens blur. If you increase the number of samples to get a decent look the render times go up exponentially. If I was trying to fiddle with extruded text in AE I would use C4D Lite. It will do a much better job extruding text.