Hi Roger, welcome to a great forum with real good people. Lots of us are either doing what you are trying to do, or have already achieved our weight loss goals, so you are in good company.
Excuse me if I ramble in this post, but it is late and want to answer your questions.
Its funny how when we get older and complete a phase/problem in our life, look down, and wonder where the hell that gut came from. When my father-in-law was fighting and dieing from cancer I gained 40 lbs, and that was on top of the 30 from the time I quit smoking
In addition to what has been mentioed, my first bit of advice is to bundle yourself up and take yourself on some evening marching parties to get those juices flowing again. I can't stress enough how quickly just moderate activity (outside of your current routine) can help your waist line an increase your metabolism.
Once you develop a routine then work on your diet (cut calories). Just a little progress can really change your attitude toward achieving larger goals. I don't think at your size a goal of weighing 285 by March One is out of the question, as the first few pounds go fast. Once you reach some of the smaller goals, the larger ones don't seems so impossible.
Spend time with people who support you and have similar goals, or ones that have the lifestyle you desire.
A fellow your size could easily need 3000 calories a day to maintain your weight. Just for giggles, add up your daily caloric intake and you may be surprised. Cutting one meal in half (I used Lunch as it seemed to be my biggest meal of the day) you can remove 500 calories a day. According to my math, you'll shed a couple/three pounds a week at first. Although I'll caution you against cutting back on the chow too much. You can end up loosing muscle, which you DO NOT WANT TO DO (I went at it too hard and should have taken in more protein calories, now I'm a pip-squeak trying to bulk up).
You been through boot camp, so you know you have what it takes, regardless how long ago it was. Shut your mind down on the fatigue and hunger pangs...just like I know you used to. Push yourself, you know how.
Last Christmas I weighed 235/40 and I'm now down to 165 (have been there since October). It was slow going at first, but once it got light enough, and warm enough outside (anything over 40 feels warm after this crap were dealing with now...I'm in cleveland...same weather) I started riding instead of walking. By June going distance was not a problem.
I wish you luck, and if I were not a Navy man, I'd give you a brotherly Semper Fi!
And talk to your doctor before you start any training (diet and exercize)program.
Hope this helps,