As far as I know, there are two major ones in the US.
The Paintball world has many clubs and associations. The main one being PSP for speedball and the SPPL for scenario. There are also college leagues as well as entire communities dedicated to Paintball such as techpb.com
Anywhere from a few to hundreds of thousands of dollars.
At most places, and all professional leagues, yes.
Due to the multiple amounts of league, it is impossible to determine the exact number of "pro players". You must take into consideration the number of leagues, divisions, and rankings.
Currently there is no international league that country teams face off in. There are only country, and region wide tournaments and leagues.
Most leagues start after the summer season, World Cup is typically held in Florida in October as an example
Check your town hall or go to your city website for rules or restrictions
Two leagues: National and American
1 foot = 0.000063 leagues.
70 leagues
No it is not, we have many paintball fields in the area.
The Negro leagues were US professional baseball leagues. The term is usually used to include 7 leagues, also called "Negro Major Leagues" which began in 1920.