Manipulating Sounds

Hi guys,
I have to load the sound effects for a level of a game. There are lots of sound files, let’s say 100, maybe more.
I have 2 questions about this:

  1. In a case like this, when i opened so many audio files, i have to close those files when i don’t need them any more (calling some method)? or just eliminate any reference to those files? i mean, to free resourses.

  2. It is a good practice to load all the sounds (base.loader.loadSfx() or music) in a loading stage or load and play when you need the sound? to avoid delays. I don’t know if the sounds are streamed.

Many thanks!!