Try to buy just enough for your hamster for maybe a month or so - this should be about the size of the packet anyway. Some owners also take to storing their pet food in the fridge. No, hamsters do not generally have a greater liking for sweet stuff. In such a case, you have to bring your hamster to the vet to get the substances removed. Your hamster will do great on his normal hamster food.
Food containing too much sugar can upset anyone's diet.