Yes lots of ideas
As for camera shops, there a 4 or so on Elizabeth street, west side, between Lonsdale and Little Bourke. Whatever you do don't miss going into Michaels Camera Store (cnr Elizabeth and Lonsdale) and go upstairs to look through their mini camera museum. Heading south JB is almost next door and has good prices (if you bargain). Teds is next, not much PEntax gear and a very anti-Pentax attitude, there's another 2 stores on opposite cnrs of little burke, the "Camera House" has a reasonable selection of Pentax gear and bodies and you can play with them (if you ask). Turn west up Little Burke and there's a store up 100m or so with a good selection of second hand Pentax gear including MF. Whatever you do though, don't get your sensor cleaned there
For day time photography here's a mini "walking tour" I do a couple of times every week.
Starting at the GPO, walk through bourke st mall, walk down union lane, walk west up little collins to Cafe Torte (take photo of cafe window, be brave), turn left down the block arcade. Zig-zag down there to collins St. Turn left and walk 50m to the pedestrian lights. Cross over and walk into the mall (has "international language book store" sign just inside entrance. Walk through there and you pop out into Centre Place. Walk though there and through Regraves lane until you pop out at Flinders street. Turn east and you can check out the station. Cross over to Fed square for photo opps. Cross over Flinders Street again and you hit St Pauls cathedral. Turn east up Flinders street for about 100m or so until you hit Hosier Lane. Walk up that to Flinders lane, then head east over Russell until ACDC lane. Phew, that's about it for now.
Apart form that there's queen vic markets (closed Mon & Wed) and Melbourne museum, and National Gallery of Victoria.
For night photography I love Docklands.
Here's some pics of the places I mentioned.
GPO
Union lane
Cafe Torta on Little Collins
Centre Place
Centre Place again
Flinders Street Station
Federation Square
St Pauls
Hosier Lane
and another Hosier Lane
ACDC lane
Melbourne Musuem
Docklands which is great at night....
I start here, looking back to the stadium
and from the same spot you cna shoot the Bolte Bridge
then go here: webb bridge
nice view from Webb bridge over south whalf
then: sea farers bridge
then to southbank
There you go, that enough for ya??