I must update this request, since my knowledge of Cubase is improving and i can be more precise. I am now in 10.0.60.
The operational situation is: I have an almost full song already developed by musicians, and want to improve the mix by importing some loops. I audition loops in the Media Rack miniplayer in the Right Zone one after the other until I find something that matches and then import into the project.
In fact Cubase Media Rack enables me to listen to my ACID commercial libraries at project root key and tempo.
This is done by transposition, for key, and Zynaptiq - pro time for bpm.
My 2019 problem was that some ACID loop libraries were not recognized by Cubase: they adapt tempo but do not adapt pitch. In that case now I open the full Media Bay (F5), make the Attribute Definition visibile and set bpm and key by hand (on multiple files simultaneously), then the miniplayer in preview adapts tempo AND pitch.
If I hear artifacts, i can deselect the middle button in the miniplayer and hear the original loop, so to understand the original key and tempo, perhaps too far from my project.
So we solved 1+2 in the original post.
3 is still pending for melodic loops.
My 2020 feature request so is: please try and match the great Elastik quality of a map-to-scale feature in loops preview (their RETUNE feature) in your Right Zone Media Rack.
In Cubase after import, I can engage Melodyne ARA and map to scale, but I should import into the project, this is not practical when I have to audition many loops. The map-to-scale feature is better than transposition because singole notes are shifted by a semitone or two, the result is more realistic. Besides, the relations bewteen notes are changed and the melody/the chord sound completely different, this injects new life in the melodic loops. Of course I understand you should change Cubase (not having just root key but also a scale attribute in addition, e.g E min) and put a young willing programmer to add the scale tag into your whole collection of loops…
The program that might act in the background to do map-to-scale in the Media Rack miniplayer might be a sort of Zynaptiq algorythm.
Thanks for listening.