Can I make a widget that would allow me to see my Spotify library and/or playlists within the widget? Something like a drop-down menu would be amazing, but I'm very new to this and I'm afraid to try to figure it out on my own.
Unfortunately this is not possible, last version of Kustom has "playlist" controls (the mq() function) but its apparently not working with Spotify and i cant do much about that, they should properly provide that information in the Android media subsystem but they are not doing it. You might consider reporting it in their forum.