I can tell you a little bit from the Marine side, although I think the Navy programs are pretty similar. Without an active duty background, you're not going to get much in the way of financial help from the Navy for law school. For officers who have already been on active duty for a few years there's FLEP, which will pay for law school and keep you on active duty while you go. It's a great deal, but you need to be in already for at least two years to apply, and since it's competitive, probably more than that to get accepted into the program. If you go direct commission as a JAG, they won't pay for tuition but they will treat your time in law school as "constructive active duty," which means that in the future it will count for pay and promotions as if you had been on active duty that whole time (so you'd start after law school as an O-2 with 3 years of service time). You can get some extra money to pay back loans after you finish your initial service obligation through the JACP program (LSEDS in the Marines). Here's some info on that:
http://www.military.com/Resources/ResourcesContent/0,13964,30970--0,00.html
http://neds.daps.dla.mil/directives/7220_10.pdf
For Navy JAG, you'd direct commission, which means you'd go through an abbreviated Officer Indoctrination School in Newport rather than OCS. There's no direct commissioning on the Marine side- we go through the same OCS/TBS as the future grunts.
I'm not sure about how the JD would affect your intel selection, but if I were in your place I'd think carefully about whether you want to assume that law school debt if you don't want to go into the JAG corps (although I admit I've toyed around with the idea of going for a ground MOS at TBS a few times myself). You can be too old to go into a warfare community, but you can still go to law school in your 30's. If what you're looking for is a degree that will help you out to get an intel package, you might look into a shorter master's program (national security, international relations, something like that) that will involve less debt and probably would be more relevant to intel than learning a lot of torts, contracts, property, etc.