Most off the beach catamarans have a bendy mast. You want it bent when close hauled (sailing close to the wind) to flatten the sail, you do this by bring the main traveler to center, and then tightening the mainsheet often block to block. When sailing down wind and the main sheet is eased the mast straightens and draft (camber) is forced into the sail. Okay now if the main halyard is tensioned by a cleat it the base of the sail it forces too much prebend into the mast. Hence, you are correct, you need to have that Nicopress-swaged-ball on the halyard in the little fork thingy near the top of the mast or you will not get optimal sail camber (nor will the mast rotate properly).
I differ in thinking you have too much rake in the mast. You have no foresail up and thus you need to have the masttop moved forward by tensioning the forestay. Without the foresail, cats have bucket loads of weatherhelm particularly in heavier winds. Not familiar with the Dart, my baliwick was Hobie 16's and occasionally I would singlehand without the foresail. Raking the mast forward was needed to keep the tiller from ripping your shoulder out of the socket during an afternoon of racing. You need to experiment with mastrake in different winds to find the optimal rake to give slight weather helm when beating to weather.
There is tons of information on Hobie Cats out there. Much of it is transferable to other cats. The Hobie 14's do not (did not) have a jib.
I actively raced my 16 in ragattas in the 1980's, raced Lightnings, J-22's, J-24's and larger keel boats during the 80's and 90's.