I want to keep the audio of an interview that I did and insert photographs that illustrate what the person is speaking about. Each photo would be up for a different length of time. Is there any way to set the time for each photo or is a slide show the only way to go?
Since each photo will be on for a different length of time, you'll need to just set the duration of each manually be trimming or extending each slide on your timeline.
Also remember that if you have Video on Video Track 1, and place a Still Image, that is as large, or larger than the Project's Frame Size on Video Track 2 (or higher), it will "cover up" the Video on Video Track 1.
Then, you can easily alter that Still's Duration, as needed.
As Steve points out, one will need to do this for each Still Image, as there is no way to have PrE automatically adjust the Duration of multiple Still Images. The closest that one can come is by setting the Still Duration in Edit>Preferences>General, BEFORE Import, to get you close.