Military officer = 4 years?

The initial service commitment for most officers is 8 years total service. For ROTC and OTS, it is 4 years active service with another 4 years inactive reserve. For AF Academy it's 5 years active and 3 more inactive reserve. Certain career fields and education programs have longer commitments (i.e. pilots, navigators, doctors, etc).

The inactive reserve time isn't really anything to worry about, it essentially allows the AF to call you back to active duty in case of emergency, which is almost never done.

Nope, it depends on commissioning source and the job assigned

OCS graduates have 3 year active duty service commitments
ROTC graduates have 4 year commitments
Academy graduates have 5 year commitments

All service commitments are 8 years, part on active duty, part in the inactive reserve

Some specific jobs require longer active duty service commitments

IE: pilots - 10 years
aircrew members 6 years

most fields require 5 years. some as high as 8 or 10. and you don't just leave at the ned like enlisted can.. you must resign your commission.. and they can and will deny that.. have seen it happen a few times.

That looks more like a statement than a question. Officers have indefinite on their ID cards. You can resign your commission, however it will be difficult to do so in the first four years.

yes, unless either unfit for service i.e injury, do something your not supposed (disonarable discharge) it will cost them thousands to train you why not?

gurkas do are in for 15 years

Officers can resign from their job at anytime, A contract for an Officer is Arbitrary. And if you want to join as an officer you need a bachelors degree and or be very close to 90 credits