You can now switch people to Adventure / Creative / Survival modes with story signs. Creative mode works only in Flatlands & City of course. Please note that people do not switch automatically back to Creative in creative worlds once they are in adventure mode.
So in your stories, please make the last sign so that they switch back to the right mode. There are new signs now in City spawn that allow people to change their modes manually.
I assume that when you switch to survival mode in the city or in the flatlands, your inventory is independant of your general survival inventory, right?
No, your inventory does not change. You can set the story to clear a user’s inventory though.