Cue is the beginning of the track. Depending on player or software this is either fixed, but usually an adaptable setting. It will set itself upon first load to either the actual beginning of the track, the beginning of sound (skipping any silence at the beginning of the track), when sound reaches a certain volume level or to the first (down)beat of a track. Again, depending on gear/software and the way it’s set.
You can redefine the cue point if you want it something else (like when it’s at the beginning of sound or on another than the downbeat or if you want to skip a particularly nasty intro). Usually this involves hitting play to find the part you want to set the cue to, hitting pause, using the jogwheel to get it to the exact position you need and then hitting cue. This is the most common behavior (CDJs also do it this way), but some players/software do it slightly different.
Hot cues are cue points that users can set at places in the track that they want to be able to jump to. Like the beginning of a break or a vocal bit or any other part that you want to skip to with the push of a button.
Hope that helps on the cues.
As for the beat matching. Get the How To Digital DJ Fast course by Phil Morse. Or find any of a number of youtube tutorials.
It’s not hard, but find a course/tutorial that allows you to start practicing the correct way.
.
