Flinders Street Satationa and Southern Cross Station are the two big stations and will have staff availableto answer all your questions.

They are in the process of changing the ticket system. At present you will need to feed your card through a machine.

It has been years since I have used the tram system for more than a trip from where I stay to the CBD.

However, the public transport system is radial and extends out a fair way and you can use the same ticket on trains as well. There is an inner ans outer zone so going to the outer zone will cost a bit more.

A train trip to Belgrave then a ride on Puffing Billy a steam train through the forest to Emerald Lake is always lovely.

I'm sure the Fodors who live in Melbourne will give you lots of ideas.

When going to St Kilda try and stay there until it gets dark as fariy penguins roost on the pier and you might get to see them.

The ticketing system is being changed at the moment so best to ask at Flinders Street or Southern Cross when you arrive as today's advice may not be tomorrow's advice. Myki is going to be the new ticketing system - similar to the Oyster card in London but currently has a lot of teething problems. Even those of us living in Melbourne are confused.
Your ticket should be valid for trams, buses and trains.
You could get the train to Williamstown for lunch - lots of eating places and shops. If you are planning on shopping, there are factory outlets in Bridge Road and Harbourtown, both accessible by tram.
There is also the free city circle tram.
Hope you enjoy your visit.