Easiest method is to have one master track, then create new tracks above it and place as many pieces of media you wish on them that the video will cut to when you want it to. This assures sync, and means you never have to cut your original video into pieces and worry about losing sync. (which you wouldn't anyway, unless you did something abnormal in the project.)
Read my tutorial on making a music video on the Sundance site, it might help.