I booked it. My first question when calling the hotline was, "are you expecting to make a profit on this?"
299EUR is the final price, it includes all airport fees etc. You have to call their hotline to book/change/cancel flights. All flights with seats available for sale in any booking class are also available for AYCF.
You can book open jaws at both ends.
Short-and-medium haul are flights within Europe, to Canary Islands and Madeira, and to North Africa (incl. Hurghada and Sharm-el-Sheikh in Egypt). Persian Gulf is considered long-haul.
Beware that they may cancel some flights - some flights to Mallorca in January disappeared a week ago before I could book them. There are not that many destinations available.