Obtaining my Merchant Mariner Document?

No problem, just be sure to disclose everything as thoroughly as humanly possible. You don't need any sea time at all for an MMD, as an Ordinary Seaman or Wiper. But you may be sitting on an AB or Oiler, at the very least. Yes, your Navy sea time counts, tonnage for tonnage, at 60% sea time awarded for the total time you were attached to a seagoing command. You will still need 90 days recency (meaning 90 days sea time in the past 3 years). BUT, it only counts for certain ratings. Any time you have unrated (as a Seaman or Fireman) counts, and deck or engineering officer time counts. Then there are a few deck and engineering ratings that count as well, I don't know the engineering ones, but for deck it's things like BM and QM. Submarine time, if you have any, counts for 50% of the required sea time for a given license or document. I don't remember which page number it is from your service record you'll need, but it's not your dd214 (although they'll probably want that as well). I'll try to find that out for you and modify this post with that information. BTW, Military Sealift Command needs Navy vets, real bad. They're not a bad gig if you don't mind the family separation (18 months+ is not unheard of right now), but there's much better work to be had in the commercial fleets.

Sure... just don't try to hide it and you should be OK. You have been off the water for too long to use your navy experience for a MMD. You will have to build up at least ONE YEAR... 365 on water days... just to apply for a basic 100 ton license, however.

Yes, it shouldn't be a problem. You will have to disclose everything and they WILL do a background check. Here is a great link that will get you started. http://www.uscg.mil/stcw/index.htm