Yes! to editing the final mix. I do this all the time with prerecorded stuff to alter songs to my personal liking. Fun stuff.
If you want to do it inside a project:
1. Bounce each track to create one continuous clip per track.
2. Slip drag the begining of each clip to the same begining point (do NOT bounce).
3. Ctrl+A to select all.
4. Drag curser in the time line rule where you want to create hole.
5. Delete Special and select all boxes. Remaining clips should fill the hole.
6. Save edited project as a new one.