It's not really a ceremony, but rather a ceremonious way of preparing and drinking tea. "Tea Ceremony" is just what we call it in English. In Japanese it's called "The Way of Tea."
What is commonly called by the English as the Japanese Tea Ceremony is called sado or chado (line over o's) or way of the tea or chanyou, literally hot water for tea in Japanese. The tea served at this is green tea. More info on this can be found on Wikipedia, the free encyclopedia under Japanese Tea Ceremony.
Most surviving ceramics from this period appear to be tea sets for use in the traditional Japanese tea ceremony, or chanoyu.
In a Japanese tea ceremony you are either invited by the tea master or someone arranges a ceremony at a tea house and they invite you as a guest. However at events in temples you just need to pay for a ticket
Japanese Tea Ceremony.
People in Japan usually have a tea ceremony on special events - Japanese festivals or holidays. Japanese Tea ceremonies are also held daily at Japanese tea gardens - there are a few of them in Tokyo (see http://www.tokyo-top-guide.com/Japanese_Gardens.html). Admission fee to these Japanese tea gardens is very reasonable, and the tea ceremony is a shorter version of the traditional Japanese tea ceremony ritual. If you are coming as a tourist to Tokyo - the Okura hotel also holds a tea ceremony in a private room, this naturally costs more than the Japanese tea gardens.
Yes
Japanese tea ceremony began in Japan, but other countries and cultures have their own tea ceremonies as well.
The merchant class were able to become tea masters when the Japanese tea ceremony became popular again. Some merchants went into the tea business at this time.
Because they were bored
Tatami.
1187 CE