I agree that there are some big advantages to being at a local school for playdates, socialising, being part of the community etc.
I work in a Vic school where we cannot take out of zone enrolments (already at 1000+ kids) however once you're in, you're in even if you move. Also, as PP mentioned (both in Vic and WA) if you move into zone they must make a place available. I can't see how any school in Australia can refuse this, as it goes against the child's right to education.
The main negative you list is the main road. What are your concerns with this? Perhaps chat to the school about your worries and see what they have in place to counter any potential issues.