Official comment
First of all, if you're using a CDJ-900NXS, why are you using DVS mode? You've got HID control, just connect the USB from the CDJ to your computer and control everything digitally with more functions and better accuracy.
But to answer your questions...
1) You can't set the cue point properly because whenever you hit the CUE button, the CDJ transmits a tiny bit of audio. Because the signal is RELATIVE, the software doesn't care about the positioning of that signal, it just recognizes that it has PLAYED a tiny bit, so it moves forward. If you want it to start where you had placed the cue, use ABSOLUTE mode and it will jump the playhead to start playback at the position you cued it.
2) Again, in RELATIVE mode, the player is sending snippets of the control code to the software, and again, all the software cares about is the fact it's still moving forward. It doesn't recognize how fast it's coming in, just that the play speed is at a certain rate and direction.
3) Yeah, again, why not HID mode? You CAN NOT use master tempo on the CDJ itself, as that would distort the timecode signal being sent to the software, making it go ALL OVER the place. If you want to use timecode and MT, you need to enable it within the software, not the player.
So to summarize: USE HID MODE.