I wouldn't delete things that are paywalled. You might still earn from them. The Medium stuff published before 1st March should be OK.

As for your questions, I believe the answer is yes, you can write about all those things, but not Medium.

So, I guess if I wanted to write about how much I've made from various side hustles, I'd have to list Alamy, Vocal Media, Amazon, and then say, and 'Miscellaneous blogging'!