The individual GP events all existed before 1995, when they were all strung together with the creation of the GP series and GPF.
We had an interesting thread on this a few months back, but I don't remember all the facts. IIRC, most of the events (Skate America, etc... go back to the mid 70s).
The 95-96 season was the first to have the GPS, and they were indeed an attempt by the ISU to disuade skaters from turning pro early, giving prize money, apearance fees, etc... It was also an attempt to bring attention and hence money to the individual events which were all strugling to sell tickets. My making it a series, it was more TV friendly than idividual unrelated events that may or may not have a star skater in them, hence more money from TV deals. Pro skating was gobbling up TV contrats at the time and the ISU needed a "hit show" so to speak to compete with all of the Ice Wars type shows the pros were selling to TV.
The six events are fixed (Skate America, Skate Canada, Lalique, Cup of Russia, Cup of China and NHK) The only change in all the years is that this year, the German event was cancelled for the Chinese event to spread the events more evenly throughout the continents.
The location varies. For example, Lalique is always (or almost always) in Paris. Skate America is in a different US city each year, although cities can repeat as hosts. Etc... The GPF is in a different country each year.
The 2 LP format for the GPF began in 99-2000 with a face off, then changed to the present format the following year.