Somewhat, Blito. The Porsche is so stable and near impossible to spin off, that you should make it as low as possible and neither too soft or stiff, though it depends on the track. 60/60/1 is a good diff, specifically for Adeliaide I used 45/60/1 the last time, but 45/45 works fine too, as well as 60/45. It really depends on the driving style, i.e. how much throttle you use under braking and how sensitive you are with the throttle on exit, and how much steering you tend to apply.
As for bump/rebound, it's fine tuning, but it can make a big difference in the stability of the car when it transitions between deceleration and acceleration. Because it's also related to how the suspension handle bumps and curbs, there's no general tip I can give for that - tackle each track separately.
Down below is a link to my Porsche setup which I used in the BREASTS race on Wednesday. I managed to do a 1:30.95 with it when the fuel went down. By memories I did mid or low 31 in the Chap 2F a few weeks earlier when we raced at Adelaide again, so the two cars are closely matched over a lap. I suspect the 2F would get the upper hand in a race, because it will pass the Porsche with ease while the latter has to rearend the 2F in corners, lol. I don't know for the other cars though, not raced them enough.
http://racingleague.co.cc/hikiwaza/downloads/Adelaide%20Chap%202F%20and%20Porsche%20setups.zipP.S. Also included the Chap 2F setup in the ZIP.