I do know people who have done exactly that, but they've all had an MOS in the Army which corresponded with their occupation in the Navy Reserve. However, this may not necessarily be a requirement, although you'll likely have to attend some sort of occupational specialty training if you're not transferring from a corresponding Army MOS. See the website in the related link for more information, including means of contacting Navy Reserve recruiters.
In the Reserve, you can.
That would be the Army. The Army is the largest military branch the USA has
There are 1,477,896 active and 1,458,500 reserve personal in the US Armed Forces. This includes Army, Navy, Air Force, Marine Corps, and Coast Guard.
People ages 17-34 years old, that has graduated high school,are eligible to join the Army or Navy. There are other requirements that you need to join the Army or Navy. Also, you have to past a certain test with a certain score to join.
Five -United States Army (includes Army Reserve and Army National Guard)United States Air Force (includes Air Force Reserve and Air National Guard)United States Navy (includes Navy Reserve)United States Marine Corps (includes Marine Corps Reserve)United States Coast Guard (includes Coast Guard Reserve)
Reserve Officer Training Corps It trains officer for duty in the Army. Upon graduation from Army ROTC, you will earn the bar of a Second Lieutenant and be commissioned into the Active Army, Army Reserve or Army National Guard. The other branches have their own types: NROTC is Naval Reserve Officer Training Corps, which provides both Navy and Marine Corps Reserve Officers. AFROTC is Air Force Reserve Officer Training Crops. NJROTC is Naval Junior Reserve Officer Training Corps, which provides both Navy and Marine Corps Reserve Officers. MCROTC Marine Corps Reserve Officers Training Corps (If you put a "J" it means junior which is high school ROTC)
Reserve Officer Training Corps It trains officer for duty in the Army. Upon graduation from Army ROTC, you will earn the bar of a Second Lieutenant and be commissioned into the Active Army, Army Reserve or Army National Guard. The other branches have their own types: NROTC is Naval Reserve Officer Training Corps, which provides both Navy and Marine Corps Reserve Officers. AFROTC is Air Force Reserve Officer Training Crops. NJROTC is Naval Junior Reserve Officer Training Corps, which provides both Navy and Marine Corps Reserve Officers. MCROTC Marine Corps Reserve Officers Training Corps (If you put a "J" it means junior which is high school ROTC)
It depends on the situation - rank superiority is determined based on time of active service, so a Navy Commander in the Naval Reserve with more years at that rank on active duty than an Army Lt. Colonel would outrank him/her, and vice-versa.
The Navy and Coast Guard do, but the Army doesn't.
yes
As of February 28, 2009 1,454,515 people are on active duty in the military with an additional 848,000 people in the seven reserve components. Military army 548,000 Marine Corps 203,095 Navy 332,000 Air Force 323,000 Coast guard 41,000 Enlisted army 456,651 Marine Corps 182,147 Navy 276,276 Air Force 261,193 Coast Guard 32,647 Army National Guard 353,000 Army Reserve 205,000 Marine Forces Reserve 40,000 Navy Reserve 67,000 Air National Guard 107,000 Air Force Reserve 67,000 Coast Guard Reserve 11,000 Total Reserve 850,000 Other DOD Personnel 97,976
Approximately 1.5 million active servicemen + 850,000 in reserve in the Army, Navy, Marines, Airforce, and Coast Guard combined.