ndw, I was a foreign student coming from a secondary education system very similar the one you have in Australia.
I was on a scholarship for 3.5 years. I only paid full tuition during the first semester then I qualified for free tuition. So not all scholarship opportunities are closed to international students.
I think some places like MIT also offer generous financial package to foreign students.
I've been pretty much on my own since I was 15. I managed all of my finances, made all major educational decisions, and I did have the EF needed to study 4+ hours every day since I was 16. I have ADHD (confirmed) and most likely developmental coordination disorder. At the end of the day, I came out okay so I'm sure your DD would manage everything just fine, especially with your support.
The biggest difference for me when applying to US college was that I had to "market" myself as a student/applicant. That was rather a strange concept for me and still is.
On a side note, I do know a student who currently attends Georgetown. I'm not so sure if she loved every minute of her college life and it seems that she was rather unchallenged but the opportunities she had for networking socially and professionally were pretty amazing.
