audio

So I am beginning to come close to finishing my gamecube portable, but it seems that Murphy's law is in full effect- as my gamecube has developed three issues that I don't know how to fix. If anyone has any idea what is going on with any of these issues, your input would be greatly appreciated...

So my goal is to have 4 audio jacks each with individual volume control. I'm assuming I'm going to need an amp. I'm not familiar with anything audio really so any help would be greatly appreciated. The console won't be running off of batteries, its running from the wall if that makes a difference.