What information should an outline for an informative essay have

Well, it mostly depends on how descriptive you want to make it but these are the main keys.  You can pretty much shorten everything down so that it takes up less space and time.  Some ways to do this is to just cite where you got it from and include bits and pieces of the sentence you are using.

First paragraph: Hook, background information, thesis. 

Body paragraphs: Thesis, evidence, analogy (rephrase the evidence in your own way)

Conclusion: Summarize the whole essay, but don't put the same stuff.

Hope this helped, have a great day~