Here's my experience. I'm on 6.14.2:
1) Under the System settings you can in fact change the interior lighting, and it does seem to work on my car. "00" is the brightest setting, then "01" is the dimmest up to "10". It seems to dim both the command center and the speedo display. I currently have mine set to "03". There is also some sort of ambient light trigger. Once issue I've seen is that in slightly dim light, like a cloudy day, the screen went to "dim" mode and was barely visible.
2) Not sure what you're asking; while a call is in progress all other audio is disabled. In my car, every time shortly after the call ended the audio resumed. I did once have no audio after the call ended (I tried radio, sat and BT) until I shut off the car and waited a couple minutes for the shutdown.
3) I don't think there's a way to defeat this. Truthfully I wouldn't want to. I've already tried to exit the car while still in "gear" because it's silent in stealth mode.
4) This has been a known issue, and I've had it happen to me on 6.14.2 once. Since then I haven't messed with it too much, but the one Sat preset I set up since the erasure has held every day since. I'm confident enough now to go set them all up again and see what happens. Interestingly, on the radio the Auto-stored presets seems to hold but the user-defined ones didn't. Again, I've only tried it once so I don't know if it's persistent.
5) Yes, you can name each fob. Click through the System Setup Screens and where you see "Fob 1" or some such, click on it and you can rename it. I've renamed the fob I use to my name, for example.
6) See my answer to question 1
7) There's a hidden "software status" screen discussed on another thread on FiskerBuzz you can display. It doesn't tell you the SW version directly, but apparrently a dealer could interpret what it does say to divine the version number. Asking for a clear display of the SW version has been discussed at length in several other threads. The short version is "we wish it did"
8) The solar screen is currently broken. It's also permanently stuck on "February", it's just conincidence that happens to be the current month. I had heard at one point they were just going to remove it altogther, but the latest info I recall (from this forum or my dealer, I can't recall which) is that it's on the list to be fixed but is lower priority than some of the other SW issues they are dealing with. Frankly, this makes sense to me. I'd rather the Check Engine Light stayed off and the presets held before they invest resources on the clever but largely cosmetic Solar screen.