A constitution is a statement of the basic principles and laws of a nation, state, or group, such as the U.S. Constitution. Another very common meaning of constitution is the physical makeup of a person. So think of a constitution as how a body (yours, the government's) is set up. If you have a strong constitution, it means you don't get sick very often.
I think the focus of the story is on Beowulf as a hero rather than a king because it is his heroic deeds that lead to him being offered the throne. Also to be king one must possess some type of heroic qualities in order to rule a land and its people.
Cloak vs Cape. The difference between cloak and cape has to do with the appearance of each clothe and the purpose for which we wear the clothe. A cape is more worn for fashion while a cloak is worn to protect the wearer from the elements such as rain and dirt. A cloak is a dress that is mostly one piece and covers the top portion of a person completely.