For submitting, you have to choose the publication from the settings while editing a story. If you click on the 3 dots next to the publish button, you should see an option to "Add to Publication" then choose the pub from there. Then click Submit/publish as normal.

The tag just helps the pub get a bit of growth and visibility. It's not a hard rule to follow. So if you prefer to use your 5 tags for something else, there's no problem.

You can see all stories on the pub's main page. www.medium.com/ride-the-wave.