There is a setting in the nav system that is something like automatically revert to map display. If you set this to "off" it will leave the display on the audio page until you change it. I'll try and look up the exact setting when I get home tonight.
The digital temp gauge is oil temperature and the analog gauge is coolant temperature. At least on my IS-F, it takes quite a while for the oil temp to come up. Usually max I ever see is 3 bars, sometimes only 2 bars if it is cold. This is after 18 miles of highway driving in the morning.
Jeff
08 Smoky Granite Mica IS-F