Changing LAN IP address

If everything is properly setup - Yes.

The Interface will reload with the new configuration and the Zone Configuration will stay (if not changed in the mode). 

In Any Case, you can actually connect via Serial or Keyboard / monitor to the XG and change it back. 

Morris,

I advice you to change the IP via cli and not via UI. Through UI, in some cases, the IP did not change correctly. Via cli is better. I guess is option 1 and then follow the wizard.

Regards