On the marriage cert, Albert's occupation is "Contractor" and Archibald's is "Gentleman".
Archibald's death cert should list his children and confirm whether he had a son Albert. As deeess said, it does seem that a number of the children were not registered.
Try posting an enquiry on the Tasmania board to see if anyone can go to Tas Archives for you to check the church registers, probably Richmond or Westbury. Though many births were not registered, most children were baptised.
The same applies with Mary FARRELL in Victoria. If you know where to expect her baptism to be you can try contacting the church archives of her religion. Just Google to find contacts.
I wouldn't be too concerned about the mother's name, at least he may have the "Fitz" right! In my experience, men were often hopeless with their mother's names.