In NSW, it's the NCAC. (Can't think of what the acronym is right now) I'm not sure if they are the same governing body in all states...gotta pick up DD from school, I will come back and expand!
No NCAC ceased to exist in 2011. Everyone is under ACECQA - however you are governed by your local authority. ACECQA is the overall body, and each state has sub bodies - so in Qld it is OECEC (office early childhood ed and care) in NSW I believe it is DOCS (not entirely sure).

The space issues you mention are a licencing issue - there is a legal sq meterage required inside and out per child. The assessment and rating process that all centres must go through (which was formerly NCAC National childcare accreditation council) is more about the quality of standards that are being used in the service, as well as legal ratios, etc.

Thing we are finding in Qld at the moment, the OECEC is so very busy assessing centres, they are not doing their regular compliance spot visits like they used to. Where once they came maybe 4 times a year, maybe more, maybe less depending on how happy they were with your service, that's not happening so much now. I had a period of 18mths with no visit and we are almost at the same time since again - we are a great centre, so they do know who they need to keep a close check on but just the same, it allows centres to break the rules more easily when this is occurring.

As for the sun thing - there isn't exactly a law as such, but a requirement that centres have sunsafe practices. Every centre should have sunsmart policies and guidlines to follow - yes out of the sun between 10-3 - this does't have to mean staying inside though, my centre has big verandahs, trees, shade sails and covered sandpits so children easily can play outside - we are always in between 12 and 3 though in a Qld Summer!

Don't quote me exactly, but the space requirement is something like 1.5mtsq per child inside and 5.mtsq outside. This actually comes from building regulations and isn't in the childcare regs or guides themselves.