Not sure where you get the idea that Traktor can do something for you in this respect?
Rekordbox DJ now has PulseLocker integration too I think, so that could cover (part of) your internet music availability. It’s a paid service but it does come with the mechanical rights taken care of, so you are allowed to play that music in public (as opposed to Spotify and YouTube, the latter being totally unprofessional and insufficient in quality IMHO).
Serato offers the same options.
For those rare occasions that I don’t have a request AND I feel I need to meet it (usually if the people paying for the party have a request), I’ll just buy it on iTunes on my iPhone which is hooked up via mini-jack to RCA lead to the aux input of my controller. BTW you could hook up your Mac phones output to the aux of your XDJ too I would think.
All your other questions lead me to the conclusion that it is time to step up from RekordBox to RekordBox DJ, using the X1 as a midi controller rather than just a stand-alone unit with USB-sticks. It will give you sampler options, PulseLocker integration without leaving the trusted RekordBox environment you are used to for prepping already.
With the switches on the X1 you should be able to switch between CD, USB and Midi.
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