Help with Vendor Financing from a Friend

I have a friend who has a portfolio of commercial properties throughout different states in Australia. He’s looking to retire and we’d like to structure a deal where I bring little to no money down as well as try to mitigate his taxes and the stamp duty. The properties are debt free and he’d like to get some cash out now so we’re thinking of possibly financing the properties and that will act as a cash buy out and then the remainder of the purchase price will be Vendor Financed either through an Installment Sale or a Lease Option. Capital Gains Tax and Stamp Duty and any costs in me being a US Citizen buying investment property in AUS to be paid using some of the money from the Cash Out Re-finance and then I will just add those amounts to the back end of the Vendor Financed amount. Once equity is built by loan repayment the i would as the Buyer then refinance to Buy Out the Vendor.

If Seller were to Re-finance properties, can those Loans be assumed buy the Buyer?

Can you Buy property Subject-to an existing mortgage in AUS?

Would it be better to do a Lease Option if the Loan cannot be assumed?

Instead of buying the properties, could a deal be worked out to buy the Limited Liability Company that holds ownership to the properties be a better solution for Buyer to assume the Vendor’s Re-fiannced Loans? This way the Buyer is buying the shares of the company from the Vendor not triggering any need for new financing?

Any help/advice is much appreciated.