unfortunately 1 prize per household doesn't apply for SA.
no. but the $100 prize clause does. See reply I received when I questioned them
This also applies to SA residents, SA residents can win more than one prize in the same competition (the SA Gaming Authority differs to the rest of the country) however the 365 day rule still applies, meaning they can only enter if they have not previously won a prize value at $100 or more in a MCM promotion in the past 365 days