Ooooh I remember having a Care Bears party when I was a little girl (about 5) - I'm 26 now tho but it was still the loveliest party I can remember (it's only through talking about it years later that I remember the finer details however)
My mum did many of the things you've said with the wall decorations and table centre-piece.
I imagine back then things were more readily available but even so she used a duvet cover for the tablecloth which I was then allowed to have on my bed - I would recommend eBay for this today as I'm sure there are some of the older care bear's knocking around.
For the centrepiece she used my own teddies all sat in a circle with the backs to eachother. I think you can get ornaments now so how about getting one of those cheapy cupcake stands, the cardboard ones, and put beads and care bears on there?
I bet there are places online that allow you to download and print care bear pictures so you could use these as placemats and the children could colour them in afterwards (might be an idea to have some spares tho...)
For wall decorations my mum bought just put posters up everywhere but how about getting some wide florist ribbon and bows and creating swags to put up with co-ordinating balloons ?
Depends how far you want to go really?
Sounds like a lovely party that you want to make really special for your daughter :) xx