Arriving in Sydney, I breezed through customs, flew through Immigration, then bought a phone card and called Ethan (details of conversation private). THen I bought some postcards and stamps. I couldn't find a mailbox. They are sitting next to me on my chair right now, but I plan to ask the front desk if they can mail them as soon as I am done here.
After purchasing these sundries, I headed out to the train station. From my research before I left, I knew which train and which times to take.