Neither - to the recordings You can batch-add them though by selecting the appropriate checkboxes in the relationship editor (if all of the recordings are by the same orchestra and conductor, just one click on the top checkbox for the album will do the trick).
Vocals, and then select choir. Similarly for instruments on releases with those, instruments and then piano or whatever.
For linking works, there’s nothing better without userscripts, but see The Classical Editor Toolbox for a list of userscripts among a lot of other stuff. For everything else, the batch-editing covers it.
Also, minor things but ideally the track titles would look like “Liebeslieder-Walzer, op. 52: 3. O die Frauen” or something to that effect And looking at the cover, the release title would probably be “Symphony no. 2 / Liebeslieder-Walzer, op. 52”