I know a few of you out there keep parrots/cockatoos, so was just hoping for some advice on breeding my new pair

I have an old log in there that we made a hollow in with a chainsaw, so it is literally a square nest about 45cm deep, 30 by 30cm wide and sits on the floor, about 1.2 metres tall. made from some kind of eucalypt... maybe lemon scented? can't remember. was put in a number of years ago basically for something for the lone cockbird to chew on!!
BUT, the other day i saw the boy, Mitch, sitting inside the log chewing at it and dropping the "shavings" inside... there are quite a few at the bottom now. then this morning i saw the hen, Tish, having a look inside...
my questions are:
1) do i need to find another nest log and hang it up off the floor?
2) is the nest deep enough?
3) do i need to put anything inside it for them?
4) should i let them breed at any time of year, or try and stop them now and wait til spring?
I have more questions, but they will wait for another post

thanks!!!