You don't need a Birth Certificate, just need to have lodged the form - SO POST IT! lol

Anyway, not sure what the problem everyone is having - I claimed the PPL, same form, filled the part in online, took about 15 mins, and filled in the paper form from the hospital (this has the proof of birth on the back of it, hence why you don't need the birth cert. when you lodge) and took it in on Wednesday. I know they are processing it because someone rang me this morning to confirm some things...

As for the estimator, there is an online TOOL that you can use to work out if you are better off with BabyBonus or PPL - are you sure that is not what you are looking at?
To get to the online claim form, you need to log in, so if you need to register for online services. If you aren't logging on to fill out the claim, then you aren't filling in the right thing.

I would give them a call and someone will walk you through it.

The paper form is very straight forward though, if you have filled in the online claim you skip half of it anyway.

ETA: You don't need to update your income to claim the Baby Bonus, only if your income has changed.