Schools of Tea

I was wondering about the various tea schools, and where I could find more information on these organizations. I have heard that Urasenke is in general quite open to international membership, are they unique in this aspect. What sets each of these schools apart from each other?

Here is a list of some of the Tea School names I have found. Does anyone know of any more, or how to write the Chinese characters for their names?
Yabunouchiryu
Sohenryu
Enshuryu
Mushanokojisenke
Omotesenke
Urasenke