Outdoors, tennis is played on clay, grass (real or synthetic) and hard courts. Indoors it can be played on wood.
It depends on how often they play or if they are professional, then how many tournaments they go to.
It is not as much about how many tournaments you have played, as how you have done in those tournaments and the number of points you have earned.
Tennis balls are geared for different court surfaces. There are tennis balls specifically designed for clay, hard court, and grass court surfaces. Check on the outside of the tennis ball can for the type of court surfaces you should use them on. For example, some tennis balls are specificially made for clay court surfaces. Some tennis balls work on hard court surfaces both indoors and outdoors. Check out your local sports store for many different brands. You also want to make sure that the balls you are playing with are "flat". Tennis balls lose their air pressure after you play with them. You can keep them in a special pressurized tennis ball can, but these are not used very much anymore. Make sure to open a new can of tennis balls when you hit the tennis course for a match. In fact, this a rule in tennis tournaments and leagues. You can squeeze the tennis ball to determine if it is flat. If you can easily squeeze it then it is most likely flat. Or you can bounce the ball to tell. Old tennis balls should be thrown away if they have lost most of their fuzz as well.
A tennis court is 78 feet long.
Yes there are many tennis courts in England.
Australian tennis player Margaret Court won 62 Grand Slam events (24 singles, 19 doubles, 19 mixed doubles).
The net of a tennis court it 21' feet.