windows expert pls help

If a service is created to log on as a specific account user, does that mean this service will only be started by that account? Can administrator start this service? Does administrator need to use runas command to start/stop the service as defined user?

If the windows server restarts, will this service be started as the defined user?

My problem now is my service can be started properly as Local System Account. If I change it to use This account, this service can\'t start up even I use runas command.