There’s already some existing feature suggestions addressing your points, some of them have already been implemented… that’s what makes it so hard to follow up on threads with a bunch of different suggestions.
Duplicate → Download entire library or playlist in Plexamp
Implemented (this was iirc one of the features in Plexamp 4.4.0)
That one seems to be unique
Duplicate → iOS allows background downloads, why doesn’t Plex enable it
Implemented (this has been around for quite some time).
Please stick with the rules for the feature suggestion section and go with 1 suggestion per thread. I’ll close this thread because of the overlaps and already existing features.