Thanks for clarifying.
As for #1, the only way a playlist, or the songs within it, can be changed, modified, deleted, or moved is if you manually do it. Or, as you say, make a mistake and change, modify, delete, or move it accidentally. So I agree that a lock could be helpful.
For #2, the playlists are sorted alphabetically. You know the name of the playlist you're looking for, but don't want to scroll down to find it. Is that correct? I have 80+ playlists and don't find the scrolling to be an issue. But I can see how it might be with 300.