In my opinion it is not cheating to look at your teachers papers. They write them so people can read them. It is also not an ufair advantage because the others in your class can just as easily find them and read them. Although you should use your own writing style, often looking at what your teacher expects of you helps you refine your style. The teacher is there to TEACH you...it is easy to learn from example. Therefor you should look at the papers to get ideas.

Use any and all resources avaliable to you
 

If your teachers paper was on the same subject, avoid it at all costs. If you do read it, you will copy parts whether you like it or not. If it's on another subject, go for it, it can only teach you good writing practices.

You have the right to use anything you can find. If the other students choose not to, it's their loss. It's like reading a book. Look at Star Wars, it's a very religious story, but honestly, how many people can watch it and associate it with Christianity? The dumb students might write a paper talking about Anakin and how he became a Jedi, then turned to the Sith. The teacher will realize he understood the plot, but didn't go much further. The smart student heads online and finds tons of studies associating Star Wars with religion, and write a paper about the meaning behind the story. The teacher will be much more impressed.

It is not unfair if someone else doesn't use the resources given to them. Looking at the essay is not something immoral. Just keep in mind the papers would be written for two different purposes. If you're reading it to understand how papers are supposed to be written, go ahead. But it's not really going to help you any. The only way you can learn how to write well is to practice.