Great news, its a wonderful feeling when you finally get that visa :).
We are hoping to fly out about the same time as you guys with Singapore, not booked the flights yet though, we will do when we are a little closer through the house sale ie exchanging contracts, we dare not tempt fate .
OAA is on arrival accomodation & you can apply for this when you have your flights booked. I think the application includes adding your flight details to it. Its not guaranteed either so I guess we all have to have a plan B - just in case !