I plan to go to see the big Buddha by cable car and then take a bus/taxi to Tai O village. Is there an option to take a ferry back to the center of Hong Kong? If so, where can I find a schedule? Do I need to purchase tickets in advance?
The Tung Chung / Tuen Mun ferry mentioned in another answer only runs a few times a day, and doesn't bring you back to HK island...
The best way to go back to HK island by ferry is to take a bus from Tai O to Mui Wo, and then the ferry to Central.
There is a ferry from Tai O that will take you back to Tung Chung or on to Tuen Mun. You can get on the MTR at the station in Tung Chung, from Tuen Mun I think there is a bus to the Tsuen Wan MTR station.
The ferry doesn't travel very often on weekdays; I think there's only one boat then and the trip from Tai O to Tuen Mun and back is almost an hour each way, so there is 2 hours between departures from Tai O. You pay when you get on the ferry. The public transit alternative is the bus from Tai O to Tung Chung, which leaves more frequently.