1) AutoPlaylists can reference any other Playlists as Criteria (Gold feature).
2) No Inbox, but you can use a separate Folder for new files and then use Collections (Gold feature) to include/exclude Folders based on the Path Criteria. Then when ready use Tools > Auto-Organize Files to move files to the regular Folder (and thus Collection).

Collection and AutoPlaylist Criteria are executed when requested, thus their file lists are always up-to-date with any changes in your Library.

I am evaluating MM as an alternative to MusicBee. The two things that I like about MB are: you can make a playlist of playlists and new music goes to an inbox instead of directly to the music database. Is there any workaround for those features? Thnaks