All - thanks for sharing a very comprehensive amount of knowledge and helpfulness. I have picked one answer, but in reality many of the responses qualify as good and useful answers - and I have tried much of what has been suggested already, with many happy hours ahead of me for trying out the rest 
With this solid amount of feedback I now understand what made Roon so popular among music enthusiasts - it is not so much the software itself as it is the highly supportive and enthusiastic users.
I have accepted that Roon can only do so much on its own and a lot of the value it can help bringing to me will depend on my own efforts, mostly for adjusting tags and creating a good set of metadata around the music files.
I have also, finally, understood where much of the metadata comes from that appears when ripping and otherwise using software for dealing with music files: it comes from you! You enthusiasts deliver all that many, many people are making happy use of. I will try to become part of this too, bringing in a bit of my own effort to the common good.
It is a rich world - in general, but the music part of it in particular, with this enthusiast forum sticking out as something extraordinarily special. Thanks again for making this happen.