If you want more than three Wills you will need to return or arrange for them to be posted to you. The service will consult the records and reply if the Will is available. Note that if you cannot supply an approximate date you should engage a researcher as the staff do not undertake research. Land ownership can be traced at the Lands Titles Office. Often a useful way of finding the date of death as this is recorded on the Title when the property is transferred.
Electoral rolls are a way of locating living people.
Every adult has to be enrolled and in theory are listed. There are local electoral offices in every Federal electorate and all hold the current rolls for all Australia. Only the above address retains past records for SA back to 1905. Unless you know the locality of the person this facility will not be useful unless you are prepared to search every electorate. Only from 1989 sre voters listed alphabetically state-wide.