Hi Ashley,
I have a 2 year old now and currently pregnant with number two. Will try to answer your questions (some) as best as I can (from experience) and hope it helps.
1. R1000 sounds about right. It becomes a lil more when the baby starts taking solids because it's more stuff to pay for. But for now...formula and toiletries roughly is ok.
2. I've found Baby City to be a lil cheaper than other places (and to answer Q5 as well) you will get everything under one roof. Alternatively try Makro stores. They aren't always cheaper than other places... but you will find everything under one roof.
3. Can't answer this one....
4. it's really up to you what works for you and baby. Whether organic/eco...
6. I have ordered some stuff online. Really depends on the product....
Good luck