1. It says your breath becomes either a 40 ft. Line, a 20 ft. Cone, or a 15 ft. Sphere, your choice. Do you choose each time you use your breath weapon or do you choose once when you take the feat? I'm guessing it's the latter.
2. With the 15ft. sphere, how far away can the sphere be... lobbed? (spit? hocked? horfed?) Does it need to be adjacent to the Drake (So, within 15 ft.)?
The breath always emits directly from the drake. This is that effect you see in the movies and cartoons where the drake twists his head around, setting everything immediately around him on fire.