40 Year Old Making Changes In His Life

Hey All,
My name is Matt and I decided that its time to make some definite changes to my life. I am 40 years old, 5'10", 307 lbs. I have large bone structure and can carry a lot of weight pretty easily. I am sorta active...play sand volleyball weekly and just finished up a spring kickball league. But I obviously am not keeping up with the amount I take in.

40 year old Matt is paying for the sins of 30 year old Matt. I worked in a factory for the last 20 years. In my twenties I worked out 6 days a week, 2 hours a day. I weighed 185. When I turned about 30, I was offered the supervisors job and that led to 10-12 hour days 6 days a week. No more exercising and horrible eating habits followed. Because of my work schedule, I didn't get fat quickly. No it happened over a 10 year timeframe. Now its time to try and get back to where I once was. I'm not looking to get back to 185, but would completely settle at 225. That weight actually looks good on me with my frame.

I found the MFP app, and this website about the same time I joined a fitness club, 7 days ago. I am using the app to track caloric intake as well as logging exercises. I tried the interval training for the first time today on both the elliptical and stationary bike....loved it.
I am strength training 3 days a week, and cardio 3 days a week...Sundays are rest days.

I am getting a kick out of the message boards here....I am AMAZED at some of the transformations. I do have a question for the veteran fitness people. Everything I've read talks about making sure you are eating your daily calories as it can have an adverse effect to continually eat under. However I am having issues with 'burned calorie' measurements. I am getting one count from the app, one count from the machine I am on, and somewhere on this message board is a link to a calorie calculator. EVERY one of these are drastically different. The machines are always the lowest, the app is way higher, and the calculator is the highest. Which one should I be following ? I am following the machine counters but I am kinda afraid that I am not recording burned calories correctly and therefore not eating enough ? Any words of advice ???

Sorry this is so long winded, and thanks. Also wouldn't mind joining a 40+ group either if anyone will have me.