Hello
Converter snapshots the destination VM for synchronisable conversions. When converter performs an incremental sync, no matter final or not, it reverts the VM to the last snapshot before synchronizing. So, no matter what changes are being done to the disks during testing, they will be reverted. This includes any changes to OS configuration.
About the services - you don't need to stop them right before the final sync. If you set services to stop in the wizard, they will be stopped by converter agent right before the final sync.
Regards