What’s on the Tour is just to use for learning, more specific recommendations with Docker should follow what’s in Dgraph’s documentation or what the Docker community recommends.
No, Dgraph needs Server and Zero. So you have to expose 5080, 9080 and 7080. And HTTP ports if gonna use Ratel and a HTTP client.
Probably not, but not recommended. It is a standard of Docker’s own use. Each container running a service/binary. Leaving a “fatty” container is not recommended by Docker community. And it does not help at all, you do not lose anything in following the recommendations.
It can binds locally.
Do like the docker-compose.yml example. That one follows the recommended approach.