hopefully not too late
Hey,
realise that this is like a few months too late, but figured ill reply anyway.
I just did that essay yesterday, I'm not sure how I'd really structure it, but I can tell you what pieces work really well with it:
"Powerhouse" by Graeme Koehne and "The Blue Alice" by Matthew Hindsen. Not only do these 2 pieces work perfectly with both topics, but they're cool too. With powerhouse you can take the idea of the rumba rhythm and explain how he creates interest with that, and in the blue alice you can talk about the idea of word painting and also the interval of the third that's used through the whole piece.
hopefully this has been a little helpful, sorry i can't help you with the whole structure thing, I recommend just talking about how one composer takes an idea then develops it, then how the other composer takes an idea and develops it.