your questions are way to broad... I have been a nutritionist for many years so I can try to help but without knowing your age/stats, it makes it very hard to help you... You have to be more descriptive and then I can try to help...
As far as cardio goes, you need to do both cardio and weights so that you can lose unwanted fat but still maintain muscle... I would do cardio first and then hit the weights after... that is what I have always found the most effective...