Reinstate some delays needed by the code to avoid crashing, and actually explain in code comments why they're needed.

I know ds2_setBacklight(unsigned int) needs a delay before it, otherwise if done too close to another call, it crashes.

This partially reverts commit 8951fdff1aada126257e07699ea6f132cb8d2e65.
Fix the interrupts glitching sound. Put the sound back at 22050 Hz.
Stop constantly testing for 16-bit and stereo in sound handlers.

This is essentially commit 6b36e79013d4c9273a96a9783a2bccdb516f174a, but for sound instead of graphics.