Is it possible to add a widget to the dashboard that consists of a clickable list of tags, and it would be sorted by the popularity of the tag? I apologize if this exists already and I missed it.
You can configure filters bar for the any topic list on the dashboard here
Move mouse over the "Populars topics" for example and click "setup"
Then check "Show filters bar" option.
You will see filter bar at the top of the topic with ability to switch and filter using existing tags.
Also it's possible to create html block on the main dashboard and manually insert tag names and links in it. It's can be temporary solution without tags sorting.