I would like to enter some of food52's contests but I'm Australian and live in Australia. Can I enter and potentially win?
Yes, you certainly can! The only caveat is that occasionally we offer physical prizes to the winners, and we typically can't ship those overseas. But if you have someone who can receive them for you in the U.S., there shouldn't be any issue.
The rules (https://food52.com/contests...) say nothing about having to be from any specific country, so I bet you could enter.