Apple Music vs Spotify

-If I subscribe to Apple Music, is there still a way for me to view just my local library, or is it always mixed in with my streaming library?

I was worried about this too, but took the chance and started the free trial of Apple Music earlier in the week. My library seems to be fine, segregated from the streaming service.

-Can I assign my own iTunes metadata (genre especially) to streaming albums?

I don't think so, but that seems a good thing to me -- any integration of Library and Streaming would give Apple an inroad to fuck up your files.

The Search function seems weird and fucked up. I was doing some basic searches to get a feel for the interface and immediately ran into problems. If you go to the Beatles artist page, scroll down to Albums and click "Show All," you don't get all of them. The only versions of Let It Be showing are ...Naked and the 2021 mix. You have to do a search for "Beatles Let It Be" before you can see the original 1970 album and the 57-track Super Deluxe version. None of the Super Deluxe versions are visible in Beatles > Albums > Show All.

I switched from paid Spotify to Apple Music a long time ago, but sometimes I'd still open up Spotify for particular music discovery: search for a particular song -> browse playlists that include that song. For whatever reason, Apple Music's search results never provided anything useful for playlists beyond the Apple-branded playlists.

It seems like Spotify might've recently updated their search results for the playlist section to prioritize playlist titles (and maybe just not include tracklists in search result criteria, which seems crazy?). Is there a way to do this in Spotify or Apple Music that I'm missing? Or is there another big music streaming service that would allow me to search and browse playlists via search for a particular song (or songs)?