Music on Mac coming from Windows iTunes issues (minor)

I have my Windows iTunes really well organized and in the Portable Library form as described by Turingtest2

Now I have recently purchased a Mac Mini as I want to switch to Mac from Windows 10.

1-

I have copied my iTunes Library tree from my PC to my NAS, and I then pick on the MAC, when opening the Music App, the .ITL file as the library that is in the Itunes directory, *itl is around 10+ MiB in size*

Oke so far so good, Music goes and does it's thing, which takes around 20-30 min.

After Music starts and everything looks good, but then I look in the Itunes Music Folder on my NAS, and from the 2xxx Directories that were there, the number has increased significantly.

I already found the cause. Mac has of course support for long file names and all M4A artist names are now the real long filenames as directory names but the original *short* directory names are also still there with the filenames in their as well.

Any ideas how to solve this?

2-

After Music has done it's thing, I see a lot of songs that have a length (time wise) of 0, i just click Get Info and it adjusts. Any idea what is causing this

3- As far as I can see the Library file is now separate from the Music files themselves?

So what I mean Music is on /Volumes/Music/iTunes/iTunes Media while the library is located in

/User/Userid/Music. So it's not that portable anymore?

Thanks for any insights you can give me, ps: I can mess this library up because I have plenty of backups of it hahahaha

OS: Is 15.6.1