No. Adoption papers cannot be sign until there is a child and legally they do not exist until after birth. Promising something before birth will have no legal stand. A mother will have the option to change her mind when she sees her child. That is only fair.
It is not always possible to rescind an adoption. If an adoption has already gone through, you cannot rescind it.
What are possible drawbacks
Maybe
You can not adopt someone who is not born yet. They can't take it out and implant it into you either. That is not possible today. Your best shot is IVF in that regard. I also doubt a woman who has decided on abortion is willing to give her child away. Then she would have chosen adoption.
Yes It is called adoption
Since a contract as this is not possible, reversing it is not needed.
There is not enough detail in this question. Your 2 year contract was for ... what? Is it not possible to renew the contract?
You can ask, but it won't happen. Adoption of non-family members doesn't happen in Australia, since there aren't any functioning orphanages anymore. The only adoption that happens is overseas adoption. Fostering is no avenue to adoption in Australia.
No.
The possible word is "celebrate" (to commemorate, or have a party).
If the seller agrees to let you out of the contract. Otherwise you are bound by what you signed.
Yes, it is possible.