Can I manage my playlists without the player connected, and then sync up later?

No.

This is by design. Emplode is not a music manager for your local PC, at least not yet. It's just a dumb terminal that connects to the database inside your car player.

This is actually very useful if you tend to move between multiple computers. Because it's not "tied to" a given PC, you can manage your playlists on any computer just by plugging the empeg into it.