#1 Reference following:
%I -- show hour(01 - 12), keep show "zero".
%#I -- show hour(0 - 12), not show "zero".
%M -- show minute(00 - 59), keep show "zero".
%#M -- show minute(0 - 59), not show "zero".
Use the #-flag will remove the leading zeros (e.g. %#M). This works only in Windows though. Other date-format can see here:
Rainlendar's help-file >> User Guide >> Date formats
#2 I'm not sure, but i think that just use standard mp3 format-file. The default file of mp3 is 128bit 44kHz stereo, and i test a file of 56bit 22kHz stereo, it also work.