Learning C# is not a requirement but a possibility to make something that was not possible in original IL-2. It is not required for making standard missions in FMB but allows creation of scripts for complex campaigns like this new mission from stillborn
http://forum.1cpublishing.eu/showthread.php?t=24954 (can be played also as a singleplayer or coop if you start a password protected server for you or your friends).