The way I like to do it is to export out the project with just the photo sequence and no music. Then import the exported project back as one video clip into a newly created project. Then add your music. Now you can control-click on the on the video clip and select Show Speed Editor from the pop-up menu. That will reveal speed slider handles in the upper right hand corner of the clip. Slide the handle to the right to lengthen the clip (slows down the duration) or to the left to shorten the clip (speeds up the duration) to adjust the clip's length and playing time to the audio clip. Alternatively, you can control click on the audio clip to reveal the speed slider, and adjust the audio clip to fit the video clip -- if the adustment to be made is relatively small.
Another way is to select the first photo in the sequence and then shift-select the last photo. That will cause the entire range to be selected. Then click on the little "i" button in the tool bar at the top right of your screen. In the duration box that appears, type in a duration that you want the individual photos to be and then press the return key. All the photos in the range will be set to the duration that you typed. Unfortunately there is no feature to set the total time in the range, so you would need to calculate in advance the total time that you will need and set the individual photo duration accordingly.
-- Rich
