Under upcoming, "King in Yellow" and "Dunwich" have "Updated!" splashed over the thumbnail - does that mean they are updated/revised similar to "Pharaoh"?

No - they are just reprints

Whenever you see the "Updated!" tag in the Upcoming section, you see an item whose status changed. For example, from "At the fabric" to "Shipping now" or "In stores now". That's it. In case we have a product whose content has been changed, we have a "revised edition" or "new edition" label somewhere.

So, don't worry