This article appears to be aimed at people who don’t have much experience mixing as most of this is overkill for the “minimum requirements” to mix 2 songs you don’t know. For a moment I’m gonna be “that guy” who mentions that we never had much if any of the track info at hand when mixing vinyl. It seems like we are all too reliant on being spoon fed track info. Whilst I would never disagree that being prepared is a good thing, you need to use your ears more and eyes less. Stop looking at your laptop. You got headphones, use them! You will be able to HEAR if the tunes have compatible BPMs and HEAR if the keys are clashing. Then you just gotta make sure you mix them in at the right time which isn’t rocket science considering the structure of music.