Where are you actually planning on heading above the snow line?
Inside or Outside the Alpine Resorts (Hotham, Falls).
Inside, you wont find any snow wheeling, and you will need to carry chains by law, outside you can drive on any of the tracks which are open (If I remember correctly, most are shut for winter). As for just visiting the snow, your vehicles will already be running an antifreeze/anti boil coolant in them and you will be fine.
If you are running a diesel, try and fill your tank up locally (in bright) so you have alpine diesel, wont coagulate in the lines. Or you can get an additive from your auto parts store, or heater oil does the trick.
As for fishing, that is trout territory, and trout season is closed.
The maps are at the bottom of this link:
http://www.depi.vic.gov.au/fishing-a...on-regulations