If you need help in Reading and English Language Arts, you may find useful information here. You can include suggestions in this paragraph, too.
Topics can include any subject matter or ideas.
Audiences can be as varied as the forms given - teachers, friends, students, company CEO's, newspaper readers, newspaper editors, etc. The third paragraph simply restates the info in the first paragraph in summary form. It is important for students to know how they will be assessed before they begin to write the answers. You can create your own rubric in order to award points or grades for the different parts of the writing according to your own needs. For example, if you are assessing a student's understanding of a scientific principle or an historical event, you would probably score the student higher for development than for language usage.