Regarding #2: The dashtop will be the tough part for getting closely-spaced stereo speakers integrated for both the driver and the front passenger. The rear channels are easier (integrate into headrests with level and delay controls). Rear passengers are even easier (integrate frontal stereo pairs into back of driver and back of front passenger seats).
This design may one day make things a lot easier: https://ifworlddesignguide.com/entry/273938-bo-for-ford-must...