Life jacket is most important or an emergency flotation device. In odd circumstances and higher wind you can become separated from the board and it can float away faster than you can swim after it. Trust me , thats scary , it happened to me and i didnt have a life jacket.
Having said that it probably wont happen

In case of a breakdown , easy. Unrig your sail. Roll up the sail , shove the mast in the middle ,lay the boom on top and tie it up with the down-haul rope. Lay it all on the board , lay on top , paddle in , reward yourself with a beer