Matthew,
I totally agree with Bryce about graphics size, especially in FCP. I use the exact same rule of thumb as he and my machine flys.
Regarding working with audio in AE, I do it all the time and find it much easier than I previously percieved it to be. A method I use is hit “LL” to twirl down the audio waveform, and jack up the levels so you can see it better. (turn down your speakers a bit for this part!)
It is usually then very easy to edit to the beat or whatever.
HTH…