1) mySound.start(secondOffset,loop);
secondOffset An optional parameter that lets you start playing the sound at a specific point. For example, if you have a 30-second sound and want the sound to start playing in the middle, specify 15 for the secondOffset parameter. The sound is not delayed 15 seconds, but rather starts playing at the 15-second mark.
loop An optional parameter allowing you to specify the number of times the sound should play consecutively.
2) you can unload the sound with
delete mySound;