I am also doing these texts and module its a good one lots to write about.
We just started Metropolis but have done Shelley and Godot now.
For related texts our teachers gave us some ideas eg. Hersey's Hiroshima, Flannagan's Question 7 (im doing these pretty sure - i think you can do up to 2 related 2 prescribed so 4 in an essay or just 1 related so 3 total) and something about the Beatles? some people in my class are also picking their own but have to check with your teacher cant be a hsc prescribed text for another level of english or another ext module. And this is an extra thing not compulsory but my teacher said some hsc markers are very stuck up so if the related is too controversial they can mark you down based on personal bias and cos its all done online now and alone cant really be changed sadly