No. But the first paragraph should include a topic sentence. This is a sentence that introduces or summarizes what the paragraph is about.
Yes it should because its an essay!
Yes, it is important and essential if we give a title of the essay because it will give an insight of what the detailed information is about so that the reader knows what the essay is about and what is written in the detailed text. One needs to make sure that the title is impressive and attractive enough that will make the reader read the whole essay. www.writengine.com/essays/
I think they do because people are going to want to know what you essay is about. People don't want you have to search for something to see if they even want to read the essay or not.