cdj 400

Hi guys, in a few days im having a gig, but there is a small problem: im getting the pioneer 400 set and im used to playing with the 2000nxs one. Im really nervous how much differences there are between them. Beatmatching without the waveforms is however no problem at all.
Another concern for me is the music on my usb: for my 2000nxs set i need to scan each mp3 file to rekordbox, otherwise this wont load. My question and concern is thus: since rekordbox wasnt released when the 400 set was, is it ok if you put .mp3 tracks on it? Without scanning or analysing them? If i put raw .mp3 tracks on this usb? Is it plug and play?
If you have tips and tricks for me, let me know! Thanks alot