Ok, Im gonna try to cover all of this.
It DOES NOT matter when in the day you do cardio. One time of day is no more effective than any another, the human body cannot distinguish the difference. The ONLY variable is the amount and type of calories you take in. If you have elevated glucose levels when you do your cardio, your body will prefer to burn that rather than your bodyfat. This is why some people prefer to do cardio on an empty stomach, but its not really necessary. You will still be burning bodyfat provided your intensity level is not so high that there is an oxygen deficite. I say, eat before if you want to, just dont go overboard.
Now, the only thing you are doing by prolonging your food intake after cardio is making your body think its in a caloric deficite. You can do the same thing by cutting your total daily caloric intake. Eating a reasonable meal after your cardio is not going to undo all the cardio you just did. Remember, if your doing cardio, your probably dieting, so just follow your diet.