#Is player data safe if I update/republish the place?

Yes — profile data goes through a migration step (ProfileTemplate.Migrate) every time it loads, which fills in any newly-added fields with defaults and sanitizes anything that looks corrupted, rather than requiring every saved profile to already match the current shape exactly. You can add new profile fields in a future update without wiping existing players' saves. What you should not do is repurpose an existing field for a different meaning — treat every key currently in ProfileTemplate.Default() as permanent once players have saved data using it.