Confusion about how Apple Music works

I wanted to do one thing: transfer the playlists on my iPhone to the Apple Music library on my Mac.

When I upgraded my OS, I lost a lot of music files in Apple Music. Over the many years I've used the iTunes software, I've deleted, moved, acquired thousands of files in a VERY disorganized way. I have iTunes libraries tucked under other directories, sub-directories, sub-sub-directories, sub-sub-sub-directories on two different hard drives. My fault. But somehow, iTunes kept working fairly predictably, and I didn't have big problems with my iTunes libraries.

But this time, after I upgraded to macOS Monterey, a LOT of music files did not show up in Apple Music. When I searched for them, I found that the files were there on my drive. Music could not "see" them. It also zapped ALL of the playlists on my iPhone.

I thought I could restore the playlists from my iPhone or my iPad. But when I connected my iPhone to Music on my Mac, Music synced my iPhone, so because (I guess) all the playlists on my Mac had been deleted, all the playlists on the iPhone disappeared. (I also discovered that I couldn't transfer music files from the Mac to my iPhone. Music on the Mac recognized the iPhone connected to the Mac, but it wouldn't allow me to drag and drop files to the iPhone.)

Fortunately, I could delete everything on my iPhone and restore it, using a previous cloud backup. That took hours and I had to do it twice when I tried (foolishly) to connect the iPhone to Music on my Mac again.

OK. I'm rambling. I am confused. Let me ask a few coherent (I hope) questions.

1. How do I connect my iPhone to Music on my Mac so that Music does not sync my iPhone and delete the playlists?
2. How do I set up Music so that I can once again transfer music from the Mac to my iPhone (or iPad) without having Music sync my iPhone?
3. Is there a way to export a playlist from an iPhone or iPad as an XML file, which can then be imported into Music?

Please don't provide instructions based on the older iTunes software. I've seen a LOT of that kind of advice. It's not helpful. (For example: "Oh, it's simple. Just go to . . . click on . . . and export the playlist as an XML file, which iTunes can then import as a playlist." THAT FEATURE DOESN'T SEEM TO EXIST ANYMORE. THERE MIGHT HAVE BEEN A FEATURE LIKE THAT IN iTunes. IT SEEMS NOT TO BE THERE IN MUSIC. Or: "It's simple. Just connect your iPhone to your Mac with a USB cable and export . . . etc." No, when I did that (twice), Music just wiped out the playlists on my iPhone. )