Much of the above seems to be entirely off topic. If I understood correctly, the OP is looking for guidance on how to process this 25/75 split agreement legally, everything else is irrelevant.
OP, there are various ways you can execute this deal.
The most effective, and the one that offers the most protection to you would be to incorporate as a company and sign over your IP to the company for which you will be the sole voting shareholder. Your marking guru can be brought in as a non-voting class shareholder whereby he would be entitled to % split of sales/profit, this would be provided for in the shareholder agreement. (obviously, all recourse and laws will be provided by Aus law)
Alternatively, you can enter into a joint venture agreement.
either needs to be prepared by a solicitor.
OP, there are various ways you can execute this deal.
The most effective, and the one that offers the most protection to you would be to incorporate as a company and sign over your IP to the company for which you will be the sole voting shareholder. Your marking guru can be brought in as a non-voting class shareholder whereby he would be entitled to % split of sales/profit, this would be provided for in the shareholder agreement. (obviously, all recourse and laws will be provided by Aus law)
Alternatively, you can enter into a joint venture agreement.
either needs to be prepared by a solicitor.