Rekordbox noob needs help

HI Guys

I was running rekordbox back when the first cdj 2000's came out, but I soon realised a controller can do the same job as them so sold them after a year and got a controller and switched to serato. 

for the past 9 years all my library etc has been set into serato crates and all has been good. 

Now I need a controller I can fit in a hand luggage case and take with me, so I'm going to buy the ddj-400. I need to set up a lot of music into rekordbox for this.

so this weekend I set about doing so, watching videos saying I can just drag my crates into rekordbox. too easy.

I am running version 4.5.0 and it says there is not a newer version available. In export mode, I plugged in my external hard drive I have all my music on, and set some playlist folders up on that device. I assumed this is rekordbox's version of crates.

I then dragged a 1062 song crate to the playlist tab i'd just created, and bang, my music then started transferring. Great. But as soon as it got to 1000 tracks, it said it could fit no more. WTF. What am I doing wrong? Why can it not hold as much as serato crates?

Secondly, once this was done and I entered performance mode, there was no playlists I just created. It just showed me all the folders on my drive. Why can I not find my playlists just created?

Thirdly, all my old music from years back is shown in multi coloured wave form, yet anything new I add to rekordbox is not showing in multi colour and has the message "multi coloured waveform cannot be displayed on a CDJ-2000nsx2 etc, as the track has been analysed in the old version of rekordbox. Select those tracks in the collection and run add new analysis data from the context menu and export them to device".

I don't get what that means or what it wants me to do.

Any help is appreciated.