My wife and I are on our second round of P90X and have reaped nothing but benefits from it. I love it! I am stronger and faster than I have ever been.
So far, we have had no problems eating primal and doing the program. The biggest lesson I have learned from round to round is my body needs protien supplementation. I simply cannot get enough protien for my body from meat, I would be eating away my budget. I have a shake with breakfast and a shake directly follwing the workouts.
P90X as you may know is designed for people who are already pretty fit. However, one can succeed with it as long as you take it slow. When we started our first round I was coming off of nearly 1.5 years of injury. I had a high ankle sprain that lasted for 2 months and a back issue that lasted for the rest. Needless to say, my body had a hard time with the program until about halfway through. I have a few friends who are hauling around similiar weight to yours, and they are having success with the program.
The great thing about the P90x program, is that you are encouraged to do what you can, not try to keep up with the guys in the videos. Take it easy and take breaks, they are encouraged in the program. The leg exercises and plyometrics can be hard on the knees. I reccomend taking it easy on these till you know your limits.
Hydrate, hydrate, hydrate. You will sweat like crazy!
You can start out with smaller free weights, and bands for pull ups. There is a way to do "pullups" with the bands hung from the ceiling, they will demonstrate it on the video's. Really you can used bands for pretty much everything.
I am in the best shape of my life due to my efforts in P90X. It has literally tranformed my life.
Just remember to take it easy, and don't be upset if you are making slow progress. You will get there. All you have to do, is push play everyday, and do what you can.
Also, invest in epsom salts for soaking in the tub, and Arnica cream from a health store. You will be sore.