1 - GB Ownership structure was in place in 1921, before the NFL was in existance. In 1983 the NFL made things official as to how ownership of teams was to be. So that was 60 years of an ownership model that was perfectly acceptable. Then the NFL decided that they didn't like it. If more cities were allowed to own teams, the investments made by owners of existing franchises would be devalued. Eventually, owners came to realize that the Packers model threatened the league structure - they did not want to have the value of their franchise tied to city-run teams. That's not so much good for money making for the NFL. Besides, what good would it be for the NFL if they couldn't blackmail cities to build them shiny new stadiums if the teams couldn't threaten to move with a ownership model that was beneficial only to the league? So no rule breaking here.
2 - It's part of the ownership structure of the Packers. Goes back to point #1. So again no rule breaking here.
3 - Everybody can celebrate how the Packers do. The rule states that only one player can jump into the stands. There's no specific "Only the Green Bay Packers can do this" in the rule book. So yet again, no rule breaking.
Feel free to keep up the conspiracy theory that the NFL prizes the Packers over the rest of the NFL and that the Vikings are intentionally punished and victimized by the league. It's a common and endearing quality of Viking fans.