I am a big proponent of CB parts and quality, however we did not have good luck with their fuel pump (and we run pre pump filter and pre carb filter). It may have been an isolated batch and may have been long since corrected but I wouldn't know because we stopped using them. Anyway, what we experienced is that while the Carter (CB) pump would not fail, it would stop self regulating and started putting out 8-9 PSI, which would flood an engine it idle and stall. Not sure of the validity and redundancy of running an external regulator with a carter, but we now run Redline pumps with external regulators. Just my experience and 2c.
To answer your direct question, 2 filters are recommended. Yes if you use the rattle pump mount it on rubber (any pump really it helps with noise and vibration). Lots of generic rubber mounts available from VW specific suppliers and Amazon. Under the tank near the front beam is a good location.