From: http://www.nrotc.navy.mil/scholarships.aspx
Total military service obligation is eight years, at least four of which must be active duty. Also, if you're not successful in getting a commision you can be required to enlist for a period not to exceed two years.
I found the details about Advanced Standing being required for College Programmers here: http://www.sandiego.edu/nrotc/faq.php#q3
I suppose it's possible the above about disenrollment only applies to San Diego battalion but I doubt it. However I haven't found it anywhere else either.
Hope this is helpful.
Very helpful. thanks!