A simplified "now playing" view for use in a car is planned.
There is no easy way to allow an app to run in 2X resolution on a 3X device. I think that creating an upscaled version would be too much work at this time. You would need larger bitmaps, larger text and larger measurements all over. Quite a bit of work.
Regarding stuck in landscape mode, the next version will allow rotation in all directions on at least the 6+, so that should fix this issue.
Thank you for the feedback:)