'Bring warm clothes and blankets' is my mantra for anyone I have spoken to about to make the move to Sydney. I have never felt so unrelentingly cold as that first winter I was here - it made an impression!
I have no personal experience of any of those schools, but have friends with dcs in a couple, and have heard stuff through the grapevine too.
Pittwater house - have heard mixed things. some people love it, one person I know pulled their dc out of the primary school and sent them to the local state school. I guess you'd have to look around to see if it would suit you. Unusually, its co-ed, but the classes are taught as single sex. I quite like that idea.
St Luke's - know lots of people with their dcs here, not heard anything bad, meant to have good pastoral care. very local to me and it seems to have a nice vibe. they've recently completed a lot of new building work.
Oxford Falls Grammar - one of my good friends has sent here dcs here and loves it. Again, its got good pastoral care. Its a bit cheaper than Pittwater House and St Lukes if that is something you are looking at. Very religious ethos, but you don't have to be religious to attend - my friends husband was very vocal about that fact he is an atheist at their initial interview and they were unphased by this and said it made no difference.
Northern Beaches Christian School - no experience at all and not met anyone who's kids attend. Maybe because it's up by Terrey Hills, so a bit away from the beaches.
Glad you're starting to feel excited. The thing I love most about living on the beaches is heading down to the beach after school for an hour or two for a swim and play - sometimes even in winter. And my 5 year old is learning to surf which seems really cool to me (older one isn't so keen!). School starts up this week, so I'll ask around to see if anyone knows of a house going for rental, just on the offchance - they come up every now and again. Otherwise, I wish you lots of luck finding a rental with dogs, and good luck with the preparations!