If you buy a frameset, replace the headset asap. Don't even think of buying the Giant seatpost or stem. Go with DA or Campy or a Chris King. DA seatpost DA headset, ITM bar and stem. Flite Gel seat.
Wheel depend on use.
Clinchers for training. I have put this thing through the mill, period. Harsh when embarking for long rides. Great for taking corners and pulling away from pack. Riders who are on the heavy side might not be recommended to ride this bike.