I'll answer the questions I can:
4: entirely depends on how you drive it. Drive it like a sports car, you'll be looking at < 20 mpg. Drive it in normal with start/stop on a highway going 60 mph, you'll be getting 30+ mpg.
5: @Suggs.OR is the best person to ask for this.
6: Yes, 100% worth the wait
alignment, check your pressures, and different tread types are all potential causes. I had the same issue when I got my rear continental A/Ses delivered a couple of weeks earlier than the front.
Also the 'I ignored the advice of other B58 owners' map -- between this forum and the bimmerpost forums, there's so many people who've blown their turbos after map3 runs I'm surprised people still do it.
Took it out to Pacific Raceways for a track day -- where do you guys put your phones for track addict to maintain GPS signal? I lost data for 2 runs because I lost signal when using the passenger side pocket (it worked fine at the Ridge).