There is no need to convert.

Just stop your old client. Rename your old FUD application data directory to DARK (or to .DARK if on linux). Then name your conf file to dark.conf. Delete your peer.dat and any addnodes in your conf. Then crank up the new wallet. Post here if you have any problems.

To answer your question about masternodes, DARK is not a masternode type anon like Dash.