Just saw this on wikipedia...
"Driftwood found by the seashore will be saturated with salt and is usually considered unsuitable for freshwater aquarium use unless a lengthy soaking and rinsing process is carried out to remove the salt."
I don't know from experience though, just happen to be researching "bogwood" and that was written there.
As far as the rocks, if you ph is already high and you are concerned about the rocks raising it, I would also either test them with ph down (a much stronger acid solution) and/or when you QT them, test the water before you do and then periodically after they have been soaking a while.
I just got a terra cotta cave made for aquarium use that raised my water from 7.8 to off the charts (above 8.8) in less than 12 hours, so sometimes it's best just to test your water to be sure.