Kevin, As Dave did, I also understood couchdb far better after spending a few hours at the command line with curl. See what put, post, get, delete do. Use Futon to view changes. It's all far simpler to understand at the lowest level in plain HTTP requests.
You will figure out testing for existence yourself after you understand the curl approach. There are several ways. Max Ogden made a very useful tutorial video. He shows curl usage so you understand what frameworks do behind the scenes. http://vimeo.com/m/18808177 HTH, Marcus
