Hi Russ, welcome to the forum
Take a look at this thread
Post #4 tells you how to download a free manual for your car
All the functions will be in the manual
It's been a while since I sold mine, but..
Yes, the fuel readout does normally go to dashes as you get down toward reserve.
Never had that issue with the stereo in mine, but mine was a 51 plate so could have been slightly different