FWIW, there are a few different reasonably priced CAN interfaces out there. I have a Kvaser Leaf Light HS that seems to do what I need, and came with some good software tools. That setup was recommended to me by a guy from Bosch Motorsport for a project I am working on. I know people also use Value CAN and some others. As Bayley mentioned, the industry standard tools that the manufacturers use is made by
Vector
The reason we are mentioning the CAN tools is that the speed is going to be easy to figure out once you sniff the bus. You WILL need to get the CAN message sorted out on a working system with the engine, ABS, and cluster all working before you pull it out. That is not a trivial job and as far as I have found, you will not just find documentation for the Porsche CAN communication.
I guess the big question is, what are you trying to accomplish?