Sync all local files not in Spotify library?

[yellowpills]

New Spotify premium user here, using iPhone, with a couple of questions:

1) I understand you can mix local files with Spotify tracks in a playlist, and then sync that playlist to your mobile, which will copy local files to your phone so you can play the whole playlist on it. However, is there a way to sync all the local files that are not part of the Spotify library, so you basically have access to all music from both pools on the go? 

For example, this morning I wanted to listen to a Vic Chesnutt song from the album "About To Choke" ...which, I discovered, is just about the only one of his albums not on Spotify. I don't want to have to manually check to see which of my thousands of albums are not on Spotify, then create playlists for them...and besides, presumably many of those albums would get added eventually, or existing Spotify tracks would get removed. This is the kind of "matching" that should be automated, no?

If this doesn't exist, is this something other people have requested, and has Spotify replied?

2) Do I need to empty my music library from iTunes before I begin syncing playlists with Spotify to avoid duplicate tracks on my phone?

Thanks,

Dave