Ah, and forgot. Haliscan Brimmed Hat is part of Haliscan set - Haliscan Jacket and Haliscan Pantaloons are two other parts. Their are craftable and any Tailor who finished this quest can get them in Steamwheedle port.

Don Carlos is patrolling between SouthShore and Old Hillsbrad instance with his pet (both elite) - exact spot is between bridge over river and tower (the one between Taren Mill and SouthShore). His Heroic version drops blue Hat which can be used for summoning his wolf.  Please note, that wow gold despawns after some time - so either do him first (before normal instance business) or reset instance after and kill only him.