I agree with AnnieBrooke...6 cans is way too much! Even if you aren't pregnant! I drink one drink each day with caffeine to avoid a headache, but after that I drink water or flavored water. But, to answer your question I agree, moderation is fine.
Six cans a day is way too much of any kind of soft drink. Either they are loaded with chemicals (if they are "diet") or they are loaded with sugar. They can have the equivalent of 12 teaspoons of sugar in one can. Try fruit juices mixed with sparkling water instead.
Agreed. 7up and Sprite are fine to drink. Drinks like Coke and Pepsi and Dr Pepper have caffeine in but you can drink up to 6 cans a day if you dont have any other caffeine sources like chocolate or tea or coffee. i wouldnt suggest doing that everyday though lol! Regarding the sugar content though that is also fine but in moderation like huajai said, you don't want to be overloading on sugar. Full fat soda usually contains like 30% of your daily recommended intake of sugar in one can!