honestly if you're new to RTE at this point i'd strongly recommend stopping using it. There's basically zero support for the countless issues this system has.

Whilst i cannot suggest a good alternative I'm sure you can find one easily enough. 

in any case to answer your questions:

EditorBodyClass - should represent the class added to the div within the editor window (inside body)

EditorBodyId  - again should similarly add an ID to the div inside the editor window (inside body)

in the webform version the editor window is essentially an iframe with contenteditable divs inside its body, of which the first is the edit window, where the id and class you apply should be added - i assume the MVC version isn't very different.

"I NEED TO STYLE THE CONTENTS OF THE EDITOR WITH CLASS NAMES. "

 you are supposed to be able to do this a few ways, but if the MVC version still uses an Iframe you'll struggle to style these with css based on a class in your main document. instead look at CSS in ContentCss which should let you define a CSS file to "inject" in to the iframe - although this process is flakey at the best of times (a bug i've requested assistance on over a year ago)