Nothing you do will cure the nausia setting wise - you just have to wait for your own head to learn to ignore the inner ear
Pick something that doesn't slide around and drive that for a while (Don't crash for gods sake!!!) as I found that helped me massively.
When I got my Rift I could do maybe 10 minutes driving an AE86 in my normal slidey style before having to stop as I felt sick.
I then drove the short tail 962 and was still fine 30 minutes in - until I span and hit a wall, that was nearly vomit central
I run all my sensors in USB3 slots (headset and 2x room sensors). My only problem is the carp drivers that mean I have to leave the headset unplugged until I've loaded home, or 60% of the time my headset is only connected via USB2. I got a warranty replacement recently and that does the same thing so I know it's their software/drivers
Once you've setup a CV1 and finished the install you shoudn't have to do the install again unless you've run that option.
Volume is controlled by 'Devices - Rift (the headset one - I'm in Win 7 so don't have the software to hand at the minute) and volume can be found in there.
The other option is to just put on your rift while Oculus is running and adjust volume with your wands (I think it's near the clock on the dash).
AC ignores most of that and you set volumes through the games own sound driver anyway - this is the most annoying part if you switch between driving in VR and higher quality replays on the screen if you forget to change the setting....
The CanAms next week may make you a tad ill I'm afraid - but the Formula Easters are perfect to teach your brain to adjust