I've got a flight leaving Sydney (Canberra via Melbourne) this Sunday and my travel ticket lists to be in T2, previously I've travelled to Domestic for T3, but I'm not quite sure if I'm able to travel to Domestic station and navigate to T2?

Exit Domestic station and follow signs to T2 rather than T3. It's just a left turn rather than a right turn after exiting the station ticket hall.

This is only my second time leaving the state, so I'm quite confused and want to take the train from Canley Vale and change at Glenfield for the airport train.

Pack in plenty of float time.

Also an off topic question since I'm travelling Canberra via Melbourne with 50 minutes connection at Melbourne for Canberra, do I have to wait for my baggage at the carousel print a new ticket (since I received one of those e-tickets), remove all the existing stickers and replaster them and load them on the new flight again? Again I'm quite new to domestic travel! What does this all mean about departures and arrivals at MELB, does that mean I have to walk outside of MELB and re-enter in departures?

You should be handed boarding passes for both flights when checking in at Sydney. Your baggage should be checked through. Upon arrival at Melbourne, after deplaning, find out which gate your Canberra flight departs from and proceed directly to it.

You should not need to go landside in Melbourne.