fwstop will stop the firewall service it will also however stop your SMARTCenter. It does not however stop any other Check Point services.
cpstop stops all Check Point services right the way down to the SVN foundation services.
To remove the gateway config then uncheck the firewall and vpn tick boxes within the Smartcenter Object.
Also read the resource on how to migrate from a standalone to a distributed environment as posted here on the CPUG website. As it is very helpful and explains step by step what to do.
http://www.cpug.org/check_point_resources.htm