Changing the display name is no big deal - it will show up almost immediately in the GAL and in up to 24 hours in the offline gal but I'm not sure it will update existing items. Existing meetings won't be affected since only the display name is changed.
If you change the alias, its a different story... meetings might break. I'll have to test that.
To change the mailbox name - in the EMC, go to recipient configuration and select the resource, right click and choose Properties. Enter a new display name on the general tab.