You need to provide a bit more info in regards to a letter of completion from what and if it is acceptable for what reason.
Completion of NCO schools.
First, there is no Air Force National Guard. It is called the Air National Guard. The military does not train anyone to become a doctor. You would go to med. school yourself and upon completion of the course, join the Air Guard as a physician.
There are actually two National Guards, but when people say the National Guard they are probably (but not necessarily) talking about the Army National Guard. The other National Guard is the Air National Guard which is to the Air Force what the Army National Guard is to the Army.
No. There is only an Army National Guard and an Air National Guard.
There is the Army National Guard and the Air National Guard.
Yes. Each state has National Guard units.
NYS does not recognize National Guard and Reserves as veterans even after completion of their military obligations. Most (if not all) State and City applications with veterans preferences do not recognize National Guard/Reserve service, regardless of how long or honorable it was. The simple rule used is if active for more than 180 days is considered a vet.
No the National Guard does not have submarines. The National Guard is primarily a ground fighting organization. The Air National Guard does provide for air support within the US.
The National Guard and Air National Guard can be (and have been) deployed. The Puerto Rico State Guard cannot.
yes There are actually 2 types of national guards. There is the Air National Guard which is part of the Air Force and the Army National Guard which is part of the Army. Then there is the State Guard which certain states have and work closely with the army national guard.
Bear in mind that the National Guard comprises both the Army National Guard and Air National Guard. The major subordinate commands of the Texas Army National Guard and Air National Guard are listed in the corresponding Wikipedia articles for each, which you can access by clicking the related links at the bottom.
The National Guard has SEVERAL Colonels.