No it doesnt!
The audio and video are linked.
You are kind of over thinking this.
I suggest you think about editing as "cuts only". You will find that you never use the entire clip from head to tail ( ie. very 1st frame , very last frame ...camera start to camera stop)
You make your IN and Out edit points where the shot works and that automatically gives you "handles" to which you can apply transitions.
Even easier is to make your IN and Out points in the Source Monitor before Insert or Overlaying it to the Sequence. YOu will see the "handles" indicated in the bottom of the Source Monitor once you have set Ins and Outs.