Screen and back side repair

Hi, I was thinking of the Apple care. I just found out that I don’t have the insurance from my carrier for my phone (I have a family plan who’s holder is by my aunt and not me), and thought of the Apple care. But I was wondering are the screens and other parts that are repairable on the iPhone like the original ones or are they like the imitation one like you would get in a phone repair shop? I have a limit time left and wanted to ask before it ends. In fact, if it’s the original and get it, since it’s unlimited repair, is it Necessary to get a case and screen protection for the iPhone?

Thanks