Just been reading your post, as for what sort of things should you be discussing?? I think the main thing is what both parties want from this, you both need to be very upfront in what you want, say for instance its no good if you want co parenting but the other party just wants to donate but without any contact with the child afterwards, so you both need to agree to what each other wants from the donation.
As for the contact that you mentioned in Australia. That maybe ok for some but once you start involving solicitors (to draw up that contract) then by law you legally have to involve other government sectors ie social workers etc.. all this could cost you thousands!! and this would be defeating the object don’t you think? after all most people are on this site as they have no means of financially affording to take the other route of IVF etc. just look at the cost of IVF for instance,