A little bit depends on your DD's age. I have a 3 year old DS and a 17 month old DD. They are both acutely Lactose Intolerant. So we stay clear of any dairy. My DS was on S26 LF formula from 6 days old and my DD from birth.
At 18 months my DS slowly started the weaning process onto Rice Milk and was on full Rice Milk by 2 years of age. I will be doing the same with my DD. We choose Rice Milk over Soy milk as Soy is not great for boys especially. But a lot of Soy products in this country have a colouring 160b which is very nasty.
As for cooking all I do is use Rice Milk instead of Cows Milk and Nuttelex instead of butter. Be careful if you decide on Margarine instead of butter as some still have dairy, where Nuttelex is made from Sunflower seeds. Though the Nuttelex can be a little greaser when baking things such as cookies so I use a tiny bit less.
I make my own Ice-cream using them, yoghurt, frozen yoghurt (homemade yoghurt and pureed fruit - nothing else), we use a spreadable cheese called Tofutti. It tastes exactly like Philly cream cheese, but dairy free. Any Coles and Woolies have it, normally with their spreadable cheeses or very close to them. We buy the Coles homebrand bread/rolls (the savings one). I also occasionaly make Sorbet so they have something different. I bake a lot, which is healther as well as dairy free - even brownies!
Everything I make is pretty quick and easy as I don't have a lot of time with 2 little ones. I do have a yoghurt maker which I purchased of store on ebay, brand new. It just cooks away and 24 hours later (we like it thick) it's ready! Then you can add what you like.
But I until you have established if it is dairy or not I would just go with the simple things. Like Milk, Nuttelex and checking your bread, etc. Just be careful with takeaways and pre-packaged foods - a lot of them use Milk products as a filler or sweetner. Sometimes it's in things you just wouldn't dream of to. After a few years I have gotten it down to a fine art. Have a look at the following links:
If you have any questions or need some other info please PM me. I am more than happy to try and help as much as I can. At least point you in the right direction if nothing else. I know there is several other Mum's on here with little ones that have either Milk Protein Allergy or different levels of Lactose Intolerance.
Have a great day!