Cannot comment on #2 through #4 but for #1 polarized sunglasses are indeed the key. The catch-22 is as per my thread posted about the HUD being washed out in the AZ sun on my M850i, I believe comes down to the windshield angle of the 8-series. I can wear the same pair of Oakley's with Black Iridium Polarized lenses (which are amazing as you can drive straight into the sun will full clarity) in the M850i and the HUD is washed out. However, in my wife's X5 with a steeper windshield the HUD is not washed out whatsoever.
Some have pointed out that using the "rotation" setting in the HUD can help but it didn't do anything for me with the Oakley's. I've just learned to live with it in the M850i and my original post was due to it being hard to see the audio presets (while using the right scroll wheel on the steering) in the HUD. The speed limit and others indicators are more easily visible but the answer to the dilemma on the presets was resolved once I realized I cannot only call out to the BMW Assistant to change SiriusXM stations but to also play albums or specific tracks from my FLAC source. Problem solved.
