Further Understanding Optical Parameter of Image Sensors for Use In Spectroscopy
I don't think that CCD includes an ADC, so the volts/count you see in different products are specific to the analog gain and ADC chip used in that specific product. Hence the numbers you calculate won't agree with numbers for other products.

As for why that datasheet is incredibly evasive about basic sensor properties such as sensitivity and quantum efficiency, that is because that is an extremely low end sensor from the early 2000s. It is meant for applications were you have enough light that sensitivity isn't important. The fact that you're trying to do these calculations suggests that this part is not appropriate for your application.

If you want a CCD as opposed to something more modern, I would look at the hamamatsu catalog. They have reasonable datasheets and you can call them up and ask questions.