1 - Yes, hotcues are only usable on cdj 2000. However you can prepare and store normal cue points, they just aren't hot cues so you need to stop the track to change which cue point you want to set it to 2 - Yes, the main differences between the 850 and 900 are -Slip mode -bigger screen -ethernet link to use computer with rekordbox -more sort options are available on the 900 due to the bigger screen. You can resort playlists by key, bpm etc. on the 900/2000 but not on the 850s. See this thread to explain this better - viewtopic.php?f=7&t=8213 EDIT: 900s also have quantised looping, 850s don't