depends on your personal view. On server 3, the NC has been shared with the entire server before and if our guild ever becomes top, every single NC will be shared with the server. I really don't see the point of being selfish with it.
It does benefit the entire community as a whole.
Anyway, I don't see a point of a gift for the guild for sharing the NC since it's technically meant to be shared anyway. It's really up to the guild's discretion whether they want to kill everyone that comes in or share it. As far as the spawning guild getting a gift for spawning the NC, the gift is already a huge amount of experience.
However, if you want to make pacts with other guilds and make them pay, it's really up to you and that's not against ToS. People pay for torches, it's pretty much the same thing. :3 But be warned, both of these situations can be tricky.
As far as the server announcement. I'm sure that could be made guild-only to fix that problem.