Don't get buttercream frosting if you can help it! I made this mistake with my daughter on her first birthday and oh my... like literally cleaning butter off of everything!
Am I correct that you want to give goldfish as favors? I would do a little research on that and consider if families actually WANT a pet. It's a great idea, but not everyone likes the idea of having a fish, as they do require some care...
We had a face painter once, and depending on the age of the kids that could be fun. It's also easy to do yourself. I went to a craft store (like Michaels) and got the Klutz brand, which comes with a brush, sponge attached to a book describing step by step how to paint. Someone who makes balloon animals would be fun too. I guess it depends on how old the kids are... obviously your one year will be along for the ride.
For the menu, I'd keep it pretty simple, but make it something the kids will eat... like pizza, a veggie plate, fruit kabobs, juice boxes and water. There's so much excitement during parties that a lot gets left and it's always easiest to do fingerfoods!
Have fun!