[Admins]

Normally you can write the game so that it doesn't use any client/clientr flags that are not necessary. Most flags don't require a lot of network bandwidth though since e.g. items use similar names and can be easily compressed when sent to the client.
The reason why you currently cannot modify the player data (except on kingdoms) is that the gserver is managing the player data and when the npcserver is handling the logout the gserver has already saved and deleted the player object. This will be changed sometime in the future though, there will be special npcservers managing the player login and rights, and the playerworld npcserver will manage the game data itself.