My eyes can't read the plan notes so this might all be in there, the collar tie section drawing, rafter ties should be in the lower third of roof height unless the ridge is designed as a beam. The ledger for the loft should be notched into the studs rather than simply nailed to them. Then the loft joists pass over the ledger and nail into the sides of the studs providing more tie to the building. Don't forget to fireblock between studs there between the floors and in all the walls that exceed 10' in height to cut down on the chimney effect if a fire does get into a wall. Best luck in May.