v2.x doesn't bundle its own FTP server (it works with your existing FTP server) so it has no way to know when users have uploaded files. But if you really wanted this functionality you could add a cron job to run, say, every 5 minutes and run:
/usr/local/centovacast/system/runascc/runascc exec ccmanage reindex USERNAME
That'll pull in any new files into the media library.
Creating per-DJ playlists is a separate exercise... this is just off the top of my head but the process would be roughly as follows:
Under your media directory create directories for each DJ, named with the DJ's name. Say, DJFoo and DJBar.
In Centova Cast, create playlists which have corresponding titles (DJFoo and DJBar).
Then create a cron job to run:
# remove all tracks with "DJFoo" in the path (i.e., under media/DJFoo) from the DJFoo playlist
/usr/local/centovacast/system/runascc/runascc exec ccmanage playlist --playlistname=DJFoo --action=remove --trackpath=DJFoo
# add all tracks with "DJFoo" in the path (i.e., uinder media/DJFool) to the DJFoo playlist
/usr/local/centovacast/system/runascc/runascc exec ccmanage playlist --playlistname=DJFoo --action=add --trackpath=DJFoo
Repeat for each DJ.
That second cron job should be scheduled to run only when the DJFoo playlist is NOT active... if you remove all the tracks from the playlist while it's active, bad things will happen.