I will deal with the issues in reverse order.
No you cant have two individuals each with an ABN. GST etc. Wrong.
GST registration is required of an "enterprise" where turnover exceeds the $75K threshold. Alternatively the enterprise can register voluntarily ie where it acquires a costly...
Buying in personal names may mean you are liable for 100% of debt if bro fails to pay his share and vice versa. Joint tenants or tenants in common ?? Do you understand the concern if its joint tenancy ? Dont sign anything until you get advice on structure ! Whatever you do will be permananent...
