How Do You Make Changes with the New Profile Pages?

I love the new profile pages, but have struggled with a couple things:

For example, if I am on the “Topic” tab and I want to add some more topics, it is not clear how I might do this. It may be obvious, but I seem to be missing it.

Also on the main profile page, you can only see a handful of “topics” with an arrow indicating you can see more if you push the button. But from the main profile page, it does this cool thing where if you run your cursor over a topic, you can see how many people and how many questions go with the topic. If you click the arrow and go to the page where you can see all the topics in the profile, you lose the ability to scroll over them and see how many people and questions are associated with the topic.