The news about McAusland isn't really a surprise - especially when you consider he's the son of one of the directors. He's only played one for the first team - against Gretna in March - but seems to do well in the reserves and could be decent cover.
The situation with Miranda is complicated by the fact he's on loan from CAI in Argentina, while there are also various issues with agents and other bits of red tape. It would seem that Franco wants to stay at Saints and the club are hoping to sign him on loan for another season, but there doesn't seem to be a timescale on a deal being completed.
Story source: The Official St. Mirren Website