Curious3: Unfortunately, there is probably a very small group of people that can weigh in on this subject as the pool of Marines with this experience is very limited. I suggest you build up enough posts to Private Message (PM) a member known as TPG. If he is still around the forum he had a long career as a Marine Officer but more importantly, his daughter became a Marine JAG within the last year. Perhaps he can help with your questions.
If I understand the paths you lay out, the first is a more traditional one where you are seeking a scholarship while in school, serving your commitment and then going to law school after your active duty tour. The second is to apply for Marine JAG after completing your undergrad. Is that correct?
Here are the paths to JAG as outlined here:
http://www.marines.com/being-a-marine/roles-in-the-corps/command-element/judge-advocate
1) PLC-Law - To be eligible for PLC-Law, an applicant must be a college senior who has been accepted into an ABA-accredited law school or must already be in the first or second year of law school.
2) OCC-Law - Applicants who have already graduated from law school and have received their license to practice law are eligible to seek a commission through the OCC-Law program.
I wasn't aware of a 2-year Frederick C Branch scholarship. Here is what I saw on
http://www.nrotc.navy.mil/fcb.aspx
THE FREDERICK C. BRANCH LEADERSHIP SCHOLARSHIP Program is named in honor of the first African American Marine Corps officer who was commissioned as a second lieutenant (2ndLt) on 10 November 1945. It is available at 17 Historically Black Colleges and Universities (HBCUs) affiliated with NROTC. The Four-Year program is open to civilians and Marines and the three and two year program is open to civilians and College Program Midshipmen that are attending or have been accepted and will attend a NROTC affiliated HBCU. This program is not open to U.S. Navy Scholarship Midshipmen or Marines in an Active Reserve status. Any eligible male or female of any race or ethnic background may be awarded a Frederick C. Branch Scholarship. Eligibility is determined primarily by attendance at an HBCU. Scholarships and benefits are the same as those of any NROTC Marine Option Scholarship student.
Good luck to you.