I want to get away from Samsung but the "Sound Assistant" app let's me control the volume of every app, kind of like a mixer. Sometimes an app doesn't have a mute option, I can set the volume of that app to 0 without effecting the volume of whatever music I'm listening to.
I also like to listen to my local police scanner and music at the same time. I can set the volume of the scanner app low enough to not really bother the music but loud enough that if something happens I can still hear it and pause the music.
I can't believe Samsung and their app is the only way, but I haven't found an alternative.
Install BiglyBT from fdroid. That is a torrent downloader for android. It has a search function to find torrents. Or you can search torrents using any number of websites.
As for quality and size.... At this point in your journey you'll have to sort and filter manually for those.
Also, you won't find many guides for android and everything does lean heavy on PC. So if you can afford it eventually get yourself a cheap laptop, it'll make things much easier for you.
Good to know, thank you for the heads up.