Mornington Peninsula Tourist Information
http://www.visitmorningtonpeninsula.org/ is a pretty good start for figuring out other stuff to see and do on the Peninsula.
http://www.visitmorningtonpeninsula.org/ has an accommodation booking facility.
Cape Schanck Light Station Accommodation. Right near the finish line and the pickup point for the buses to the start.
Mornington Peninsula Shire Foreshore Camping stretches along the bay side of the Peninsula. Sections 4 and 5 (McCrae) are fairly close to the Dromana start line.
Other Foreshore camping on the Mornington Peninsula.
Big 4 Kangerong Holiday Park Dromana
Marshall's Holiday Rentals. Mornington Peninsula Accommodation. Minimum stay is 3 nights.
http://www.fapas.com.au/home The Frankston & Peninsula Airport Shuttle will get you to Dromana from Tullamarine airport.
http://www.metlinkmelbourne.com.au/ gives public transport options, but would require half a dozen changes between modes/vehicles, if used to get from Tullamarine airport to the Mornington Peninsula.
http://peninsulataxis.com/ if you need a ride while down on the Mornington Peninsula.