Housing Trust homes can come in a multitude of styles, designs and sizes. The term housing trust refers to the (well, here anyway) The South Australian Housing Trust which since 1942 has held all it's property for and on behalf of the Crown and was created for the purpose of building or otherwise providing dwelling houses for rental or sale.
I guess it means that most of the homes are going to be old too because it was first established in the 1930's and as Melbear said they tend to be pretty small.
Sale by tender is pretty much exactly what Melbear said it's like a silent auction. The house is displayed for sale without a price and all details including section 7 statements (just like an auction) are displayed until tender is closed. During that time interested parties put in offers which are sealed in envelopes and all presented on one day in front of the vendors. The vendor can then choose to accept or decline which ever offer they desire if one at all.
The benefits for the vendor is that marketing without a price targets all buyers and can generate a lot of different offers because everyone needs to submit their BEST offer at tender.
For the purchaser I guess some people don't like auctions so the idea of a confidential bid is sometimes appealing and can also prevent bidding from getting out of hand (Buyers tend to spend 20% more than they originally plan) when the purchaser is competing against other bidders.