For the Nudging of multiple Assets, have you tried Selecting them all, and then using the Cursor Keys (arrows) to Nudge, one Frame at a time?
For the ramping up/down of the Audio Volumes, there are several ways to do that. Keyframing the Fixed Effect>Volume (in the Effects Control Panel) will allow one to adjust the Volume up/down over time. If you have never done Keyframing, then I would start with the Help File, as there are a lot of things to learn. Once, however, you have concepts and mechanics down, Keyframes are easy, and so very powerful. This article discusses several ways to adjust Volume/Gain, and might be useful: http://forums.adobe.com/message/3472343#3472343
Good luck,
Hunt