How to restart sync gateway to work?

Sure, I will uninstall couchbsae server and couchbase sync gateway. Will do from scratch again.

{
	"log": ["*"],	
	"databases": {
		"db": {
			"server": "http://myipaddress:8091",
			"usernam" :"admin",
			"password":"password",
			"bucket": "bucketname",
			"users": {
				"GUEST": {"disabled": false, "admin_channels": ["*"] }
			}
		}
	}
}

Here really required to give username and password and assign role in couchbase UI or else can i make it public?

I want to sync all the data from the server to mobile through sync gateway and vice versa, either data was added/updated from N1QL or 8091 or any REST API, as well as from the mobile. is Above configuration is enough? Do i need add anything more?