Yay Nelle, thats fantastic, you'll love it once its done, building part can be quite stressful.
Yeah 3 year old kindy would be next year. What yr doing now would be fine as its only few hours week. I think most councils are same but you need to apply thru the kinder for 3yr old and thru the council for 4yr old and you need to apply this year for 4 year old think June they start? Just check with yr local council.