To separate the audio track from the video, highlight the audio track and hit 'U' (for ungroup).  To group audio and video events together, highlight the events you want grouped together and then hit 'G' (for group).

Fade ins and outs are easily done by grabbing the fade 'grab handles' with your mouse pointer and pulling them across the event until the desired length of the fade is reached.

The red arrows above show where the grab handles are, and the symbol that shows when the handles are grabbed is a quarter circle with little L and R arrows.