Syncing slides to soundtrack

There is background music and a number of interview clips. There are slides and video clips.
Slides need to be placed relative to the sound. At the moment the sound seems to need to lock to the beginning of a slide. This makes accurate placement of the sound impossible. Is there a way to place the sound clips so that they begin at some point other than the beginning of a slide?

On a related note, how is the playhead placed in some place other than the beginning of a slide? When using long video clips or long panning slides much time is wasted playing to he end of these longer clips.