husband is currently seeing a personal trainer. I am, at the moment, full term pregnant (actually going in tomorrow morning for c-section

So to try and make this a bit shorter, I'll get to point. I am 5'11" and currently weigh 316 pounds. I have (finally) reached breaking point with weight and want to be healthy/fit not only for myself, but also for husband and sons.
I figured out (using the tools provided here) what caloric intake should be as well as how many carbs, protein and fat grams I should be having every day/meal and looked over the beginner weight training plans.
main question is, how often should I vary the workouts that I'm doing? Also, I don't see that the workout plans include cardio, and was wondering how much cardio I should be doing in addition to the weight training. Most likely I will only be able to make it to the gym 2-3 times a week. Is that going to be enough?
I am hoping to take weight loss kind of slowly because I want to tone as I lose and try to keep from having a ton of loose skin. Any advice would be greatly appreciated!