Well...
The New York Giants share a stadium with the New York Jets.
The Oakland Raiders share a stadium with the Oakland Athletics (MLB).
in stadiums of NFL teams as decided by the league
Thirty-one There are 32 NFL teams, but the two New York teams: Giants and Jets (or Jets and Giants to Jets fans) share the new Meadowlands Stadium (ironically, located in New Jersey)
Oakland A's & Oakland Raiders
I believe only houston and Arizona have truly retractable roofs
The 49ers, Raiders, Packers, Seahawks, and so many more.
None, the NFL has revenue sharing, where all the teams get a eqaul share of all the money the NFL has earned.
There are 1000's including NFL Stadiums, smaller league stadiums, high school fields, etc. But there are 31 NFL Stadiums.
Some places just want to keep the authenticty of their stadium,Like Lambeau Field.
No two NFL teams share the same mascot, let alone six.
No, they are both open air stadiums.
there are 20 stadiums with natural grass left
There are many stores that sell NFL slippers. NFL teams sell merchandise in their stadiums and in sports clothing stores. You can also find them at FansEdge, amazon,Walmart and Hayneedle to name a few.