hi you could use an alternative like Sigma Player instead of the stock music player. It saves playlists and queues songs for playback too.

Just like Open Video Player is a better alternative to the Videos app, Sigma Player is a better alternative.

For the playback controls on the lockscreen a dev needs to help. From the back of my mind a way would be to associate Sigma Player as the default music player but havent tried it yet. Will post with results later.

Thanks.