I cannot say by only visiting Ballarat for only one day that you have a four-seasons in one-day weather like in Melbourne. Therefore, it is hard to tell what to bring with you. Just, depend about the season you go I guess ;-) However, for visiting Sovereign Hill a pair of good walking shoes will do.
Is it the camera, or is it the person behind the camera? I do not have an expensive camera and not a cheap one either. I just think that I am a very poor photographer and guess that a professional take better pictures with the same camera then I do. So, if you want good pictures, take some lessons or study your camera very well. I am just too lazy for it ;-)
Luggage and bags:
You can bring whatever luggage you like. I guess it depends on the length of your stay and what type of holiday you're going to have, whether you'll be camping at caravan parks or staying in motels.
Clothing/Shoes/Weather Gear: Weather in Ballarat these last few years (drought) has been rather dry, even in winter, so 'just in case' weather gear is probably all I'd recommend.
We have more extreme summer temperatures than winter, so bring less winter stuff unless you'll be visiting between June & September/October.
If spending a lot of time outdoors in the summer, you may want to bring some mosquito repellent. Some years for this are worse than others.
Normal clothing and shoes go ok.
Toiletries and Medical Supplies: You should be able to buy anything you want in Ballarat. Some chemists are always open late, ie till 8 pm (like UFS) so you can get medications after business hours.
Photo Equipment: The best place I find for reasonably priced camera film (100 - 400 ASA) is the Target Department Store, within the Central Square shopping complex in Doveton St Sth. There's also a photo developing store beside target inside the centre.
Camping/Beach/Outdoor Gear: Bring your own with you if you can carry it, I guess, or you can buy some here. Beach gear is probably cheapest to buy here rather than bring.
There is a large camping store Ray's Tent City opposite McDonalds on Bakery Hill, and another smaller camping/army store at the McDonalds end of the Bridge Mall.
Luggage and bags:
Good comfortable luggage on wheels.
Clothing/Shoes/Weather Gear: Depends on what you plan to do...
Nightlife - nice clothes...
Hiking and camping - appropriate clothing and footwear.
Ballaraat can get very cold during the Winter.. below freezing... so lots of warm clothing during that time.
Toiletries and Medical Supplies: You can buy everything here, just take any special medications you might be on.
Photo Equipment: Bring your Camera... you can buy film here.