Add Additional Functions to Custom HTML Player

I have had a custom HTML5 player at [login to view URL] that works well. I need some specialist functions/add ons to this including: 1. When a track is playing and then a user presses stop on that track, or play on a second track, the first track stops playing and loading. If he presses play on that first track again, it continues loading, of course. 2. Volume slider. A floating volume slider that controls the overall audio output. That guy Luke had one designed but not yet implemented. The floating slider moved with the user as he scrolled down the page. 3. As mentioned, another developer is working on creating a background image of each track waveform for the player at the moment. These images need tie into each corresponding track. It would also be nice if the background image changes colour as it scrolls along. For an example, please play a track from the site [login to view URL] and have a look at the player at the top of the page.