Two questions; We arrive in Melbourne this Friday morning, staying at the Langham. One of the first things we want to do is buy a throw away phone and some snacks for our room and car. what is the closest shopping area which fits these needs?

The day before driving to Apollo Bay (Sunday) is open; I am thinking of driving the circle around Port Phillip Bay. Good idea? or is there a better idea? I assume there are frequent ferries crossing between Rye and Queenscliff?

Go across the river from the hotel, and near the intersection of Flinders Street and Elizabeth Street, there is a small supermarket on the right hand side of Elizabeth Street.
Your suggestion of driving around the bay and crossing on the ferry to Queenscliff is a good one. Check timetables and bookings on www.searoad.com.au/
Incidentally the ferry goes from Sorrento, not Rye.

And check with your rental car company as to whether their insurance allows /covers transit on the ferry. Many don't.

Around the bay in a day is a long way. Pick one side. The Mornington is particularly lovely with a wide range of nature, food, history, wineries, breweries and a distillery.
The sand sculptures at Frankston are always worth a look.

http://www.visitfrankston.com/pages/sand-sculpting/

You can hire a boat at Frankston as well if you want.

I agree with peterSale - pick one side or the other (and the obvious one is the Mornington peninsula). However, whichever way round you do it, though the Queenscliff bit is fine, the drive up from Geelong on the western side from/back up to Melbourne isn't that interesting and you will simply duplicate a lot of it the following day when you head back down the GOR. For a day out, I would consider doing a loop up through Ballarat / Daylesford / Kyneton instead.
http://www.ballarat.vic.gov.au/vs
http://visitdaylesford.com.au
http://www.kyneton.org.au

IMPORTANT - If you do not already know, MONDAY IS A PUBLIC HOLIDAY. Check what will be open before you go.

Most tourist things should be fine.

If you feel like a walk and want a big supermarket, you could try Woolworths at the QV building. It's near the corner of Lonsdale and Swanston (Woolies is downstairs). They may have phones but if not, there are loads of shops in that area. About 20 mins walk if you go straight there.

Very close to the QV centre is the State Library. The Reading Room is really worth a look - unless you are from Britain in which case you might think 'they call THIS a reading room?'.

There are lots of other small supermarkets and 7/Eleven type stores in the city much closer to Southbank and your hotel if you don't fancy the walk. Also just remembered a Coles supermarket on Elizabeth St, near Flinders St. This will be the one Marg, above, mentions.

I agree with the others that doing that circle drive would be a bit onerous. Also I think when I looked into it the ferry was a bit pricey. Why not drive south and have lunch at the Portsea Pub, used to be good but haven't been in years. Check out the shops and cafes at Sorrento. Lots to see in that area. Queenscliff is nice but the drive back from Geelong is boring.

Kay