for decorations i would do something like dark cloth draped on things so its like a junkyard, and maybe some fairy lights. For food do things in cats shapes or give them names like munkustrap's biscuits or Cassandra's crisps, or look at some pictures of the cats and see what food they look like, e.g victoria is all white like a marshmallow. hope this has helped.
rumpuscat
Well I'm not sure of decorations but activities...you could set up each child with their own MINI set of CHEAP face paints and have each of them paint their faces to become a cat. hmm maybe I'll come up with more
You could set your backyard kind of like the stage! Put a old truck or PT cruser here, a gigantic tire there, throw old cracker and cookie boxes around, maybe even put a moon-shaped thing on the top of a tree or something over the tire. You could even get face paint and get someone to paint cat faces on everyone! Get a jukebox and play the CATS soundtrack!
Do pin the tail on the cat! and and normal childrens party games but just adapt them so their like cats, and if it has music then just use the cats music!!! and make them drink milk from bowls!! warning! when me blioux and Milly (aka bomby & etcy) we laughed so musc we ended up spitting it rite back in the bowl cos we were just three thirteen year olds drinking milkk from a bowl with our mouths. very normal. Anyway!!! cats party yeah