To sync, connect an ethernet cable to the ProDJ Link port on the back; either direct to your CDJ or through a network switch (not a router). Press the SYNC button on the touchscreen (bottom row, 4th from the left), and select PRO DJ LINK. Press the MASTER button on the CDJ, press the SYNC button on the right side of the DJS. Done.
As for time-stretching a sample, it will do it automatically. If you want to adjust the pitch manually, there are several ways, including modifying the sample itself, or using the touch strip.