Switched from Serato to XDJ-RX, few questions!

So I just recently switched from a Numark NV w/ Serato to an XDJ-RX. Loving it so far, just stumped on a few questions, searched around a bit but couldn't seem to find a solid answer.

Firstly, is there a way to have the RX display a bar count? I know if you set up cues it will count down bars/beats until your next cue, but can I have it simply count bars progressively through the song? I liked this in Serato because it allowed me to know when a new phrase was starting by counting in proper bars. 

Secondly, what is the EXACT difference between Hot Cues and Memory Cues? I've read different things and I'm just a little confused. If I place Hot Cues while mixing will they be saved so next time I turn on the RX they still exist where I placed them previously? Or is that only a function of Memory Cues? 

Lastly, when I'm mixing I match the two songs BPM but when I bring in the second track, a lot of the time it seems to pretty quickly go off-beat, leading me to believe something is wrong with the BPM and they are not actually equal. Am I missing something? Also, is key-lock a thing in Rekordbox? I had that for Serato and it definitely made life easier at times, curious if Rekordbox has a similar feature for keeping tracks in key when increasing or lowering their BPM. 

Sorry if these are questions with obvious answers, did some searching but couldn't find any concrete answers. Thanks in advance for any help!