I just wanted you to check or clarify, your saying you have a changer in the box, but only 1 disc slot in the dash?
If that slot is not specifically labeled as a DVD slot on the right side, and only has 1 button for ejecting then you most likely don't have a navi.
On my E60 545i, there are 2 slots in the center dash, one upper one for CD's to listen to, the lower one is that DVD slot for my navi disc.
The heated seats buttons will be two little button in the center dash area, but at the very bottom, where it meets the plate for the shift console. If they are not there, then you probably dont have the option.
as for the ac stuck in auto, my car glitches once in a while, but always fixes its self if I turn off the car for a few seconds. Sorry dont have any info to help on this. idrive is just glitchy sometimes.