I can answer this
As someone who has been at your point (far worse, as I started at 328 5-8 52 inch waist) I think I can give you some more specific advice. The biggest mistake most endomorphs such as yourself make is being Over-agressive and UNDER-Consistent when It comes to diet and exercise. When one starts on the heavier side it is just not possible to be able to exercise at high intensities. At over 300 pound you just wont be able to hold a high intensity(cardio) for a long enough time to burn calories. If you are serious about getting in shape I reccomend a good 2 HOURS of VERY Low intensity cardio EVERY day, absolutley no exceptions(swift walking is fine). I reccomend walking outside to avoid bordem. Over time you may increase intensity and shorten duration as your cardio level increases but i honestly would not worry about this for atleast a couple months. Same thing with weightlifting I would recccomend greatly decreasing time in between sets. I would reccomend e.d.t style training by charles staley look it up on google.
As for diet I reccomend slow adjusted changes over time. Pick certain things to drop every week and keep to your promices(Never make a promise you can't keep). People that constantly fail never realize that willpower is not given, it is something that is earned over time through gradual hard work and consistency. Only make promises that you can keep, anything overzealus will always fail. After a few months of altering your behavior patterns(atleast 4-6) I would then absolutley recommend a Ephedrine-caffiene-Yohimbine stack, as long as you ask your doctor, This will greatly assist you in reaching the next level of conditoning that you seek. Using e-c-y stack before you know how to stick to a diet will result in a massive weight rebound. As far as anabolics that is a personal choice, they absolutley work but like everything else if you choose to use them, you will get much better results if you wait first and gradually increase your intensity levels in the gym and then use them down the line.
As far a strength loss I would not worry, I have atrociuos genetics as I could only bench about 100-125 pounds when i was over 300 pounds, By the time I
got down to about 180 I could bench 315 for 3 reps and do a weighted pullup or 2 with 100 pounds. You obviously have far better genetics thhen myself so the sky is the limit good luck