Question 1: What can I put in the bin?
As far as what goes in the bin, I stick to fruits, veggies, coffee grounds, egg shells, bread, etc. They advise against putting meat, oily or fatty stuff in it. Partly for the worms, so you don't attract bugs, and partly because of the smell, I think.
Question 2: If I have an outdoor compost pile, do I need a worm bin?
This is the first time in a while that I've had a healthy outdoor compost bin. I've been using it all summer, and just keeping the worm bin at work. However, here in Utah, the cold winters make outdoor composting difficult. I plan to either bring my scraps to work, or start a worm bin at home. So, you can have one, or both, your choice!
Question 3: How much food can the worms handle?
For this latest bin, I received my worms from a friend, so I'm really not sure how many I have. I've been paying close attention to how much food I give them, and storing the rest in a bucket in the fridge. Give your worms just enough so that you don't have a bad smell of rotting food. You'll soon get a handle on how much they can take. And, as they multiply, you can add more and more scraps.
Here are some additional links. Happy worming!