Need a good beginner's setup for Bird Photography

I am an avid birdwatcher and would like to get serious about photography. That being said, I wanted to know about how I should get started and what equipment and lenses would be best. My dad is an avid Nikon fan, but I am brand agnostic so any suggestions from Canon/Nikon/Sony/others enthusiasts would be welcome.

A few questions that I have include:

- Approximately how much will all this cost?

- What would be a good lens length and type? I would like to get serious about raptor photography specifically, so would there be any specific lenses necessary for such a pursuit over 'normal' nature and bird photography?

- Any beginner's books that might be worthwhile reading so I can learn the ins and outs?

ANy help would be greatly appreciated, especially from nature photographers. Thanks in advance!