1. In general a cTrader account is required for the plugin? A 'pure' FIX API account does not work or at least not out of the box?
Yes. As far as I can tell, there's no such thing as a functional "pure" FIX implementation, so this one targets cTrader specifically.
2. Using your example AssetsCT.csv what do you mean concerning the dash in the assets names? AUD/USD e.g. has the symbol 5 there, selecting it in the strategy must be with asset("FXCM-5") or asset("5") or must the symbol be written as "FXCM-5" in the assets.csv?
The symbol being passed to the plugin (the one in the last column) must be "FXCM-5". You can name it whatever you want in Zorro and use asset() with the Zorro name.