1 has been answered, I can help with the A10. The exact number on the cannon's rate of fire is classified so books are estimates. That's the reason for the disparity from text to text on most modern weapons.
I am not 100%, but it takes approximately 2 years from the Academy for most students to enter duty as a pilot.
The Differance between the Air Guard, and the Reserves are simple. The Air Guard are state forces, and the reserves are fedral. It takes the president to activate local Guard forces, for other then state emergencies. There are acceptions and but that is the general rule.