Each room decides it's own methods and percentages.
But they also change them from time to time.
Pokerstars has become a big offender for frequent changes recently. Only partly due to various countries changes to online gaming taxation.
For the current answer you need to go to the current source.
https://www.pokerstars.com/poker/room/rake/
It should re-direct to the appropriate country ( www pokerstars .CCC /poker/room/rake/)
Yes players sitting at the same table but from different countries could be charged or more commonly rewarded differently.
There are no stupid questions here.
In the past Pokerstars rake adhered to a
“no flop, no drop” policy, meaning that no money was taken out of hands that end on the first betting round.
For the day on which anyone in the future might be reading this they would have to check with the current BetStars.com policy for their location.
The other aspect to this is rakeback or rewards.
In the past some sites rewarded all the players at the table while others only rewarded players in the hand.
Rewards meant player status (silver, gold, superdooper, etc) plus points to redeem from a store or even a percentage of the rake collected (sometimes via a third party) with the amount dependent on status.
Confused??
https://www.pokerstars.com/vip/changes/
The 2016 changes are already set to be changed again in 2017.
Any one with high volumes will have to put in a lot of work to keep up with the moving goal posts.
Unless you are turning over thousands of dollars each month, you might as well just forget about it and enjoy the game and any table winnings you collect.