They are different colors to make pulling them out easier. One medium dry bag for pots, pans, dishes and spices. All food should be protected from contact with water in the hull of your kayak, no matter how good your hatches are. All wrappers should be stuffed back in the bag when empty then kept in the hull of your boat. Remember, however, always make sure you double bag trash, even when stored in your hull offshore.
Bears can swim.
For the chef, many, many outdoor cookbooks are available. Learning how to dehydrate your own meals in preparation for your trip can also be very rewarding and is something everyone should try at least once. Fishing is also a good way many prefer to go. Dispose of fish remains as you would any food. Remove all wrappers from food to minimize dealing with waste.