The scalings are dependent on the candidature, since the students of a higher capability are more likely to do ext2, it will probably be scaled higher.
Ext2 is basically "free", you do a major work that is marked externally, and there is no exam. You can write short stories, an essay, poetry, make a video, write a speech or radio play etc etc...
Ext 1 has a defined syllabus, there is an exam. My school for example studied teh genre of crime fiction. We had prescribed texts and course outline (huge bludge.....did nothing in class for three of the four terms except gossip).
Ext 2 is as hard as you want to make it. It takes a lot of work, dedication and enthusiasm, but its interesting. AS you set the guidelines for yourself, if you focus on something you enjoy and fascinates you it will merely be a labour of love. I found it hard in that a great deal of it was nothing like i'd ever done before. I did a critical response, so I had to go about learning how to structure an academic argument and did more detailed research than i had ever done before. i thought it was definitely worth it however Even if it was just an entire unit over before HSC exams began, while also taking pressure off my advanced english (which i hated) because at least 2 units of english have to count.
good luck!