It was originally built by National Jet at the behest of Qantas to set up an overnight base for the 146's.
Pretty sure it was actually built by Southern Australia Airlines (and still paid for over a number of years)
Just to be pedantic, it was not a freight shed but a maintenance hangar. Now being put to good use by Sharp Airlines.
Yes, but it was a freight shed/baggage trolley store for quite some years before someone decided to put planes in it again.