Can I connect the CDJ-3000X with another type of PRO DJ LINK-compatible multi player, or the DJS-1000, via PRO DJ LINK?

When you use only CDJ-3000X and CDJ-3000 units, you can connect up to 6 multi players via PRO DJ LINK.
Up to 4 multi players can be connected via PRO DJ LINK if you use 1 or more other models.
If your setup contains only DJS-1000, CDJ-3000X, and CDJ-3000 units, you can connect up to 6 units in total if you update the DJS-1000 firmware to the latest version.