#1 - commitment for reserves is 8 years initial obligation
#2 - Deployments can be overseas or in the U.S. Whereever they need nurses. Sometimes you deploy as a group with your unit. Other times you can volunteer to join a mission. Probably half of the deployed reserve nurses right now are in the U.S. working in military hospitals, case management, and other assignments
#3 If you don't have an RN degree yet and you are still in HS you should talk to an ROTC recruiter. The Army might pay for your college and let you get a BSN in nursing if you qualify and are selected.
#3a if you go on to nursing school first and then join the army reserve your recruiter can and should include student loan repayment and maybe a bonus for signing up with a BSN in nursing. The army reserve will let you join with an associates degree but you have to complete your BSN if you want to stay in past your initial commitment.
#4 you should ask the recruiter about ROTC. If you don't have a nursing degree from an army recognized program he can't recruit you to be an army nurse so he will probably try to convince you to become an army medic and then use the army "Green to Gold" program to become an army nurse. That is an option and the army will pay for it. But it's a very competitive route and you would have to be very enthusiastic and committed to doing it. If you are sure you want to go straight to nursing then keep him focused on ROTC or programs that pay you to go to nursing school.
#4a ask about signing bonuses and which jobs have the most. You might be interested in the better paying ones. Ask about student loan repayment. That should be in writing in your contract.
#4b you should look out for any promises that are NOT in writing. If the recruiter tells you that he can get you into nursing school then make sure he writes that in the contract. Yes, you will have a contract and it should detail the promises the recruiter makes on behalf of the army. If it is not in the contract then you can't hold the army to it.
before you get the wrong idea, most recruiters are honest but they have a job to do. That job includes meeting recruiting goal. They are taught that most people usually don't mean it when they say no. After all, you wouldn't have come to the recruiting office or called if you weren't interested.