Programmes have been designed with a particular aim in mind, and active rest periods are incorporated within each. There is nothing prohibiting you from doing more than one programme at a time, but you'll likely get better results if you stuck with just one. Some programmes are Add-Ons which you can add to a regular programme.
Losing weight, reducing belly fat, toning, getting abs and flexibility - these are great aims to have, but they will take quite some time and don't expect to get all at once. Consistency is key. Adding physical activity to your routine is a good way of toning, gaining muscle. After all, you can't see your abs if you don't actually have any muscle there. But to see them, you need to reduce body fat, and that is...