And what about the ADC?
A lot depends on how many samples per second you want. This will determine the sort of ADC techniques to use and so the chip. Basically the faster you want it the more expensive it is. Also depending on the environment it is in you might struggle to get 16 bits precision.
There are other processors with CAN buses built in but they are not at the hobby end of the scale like the arduino so the support you get is not as hand holding. Have you read this:-http://en.wikipedia.org/wiki/Controller_area_network