Photography
For photos you need to check the licence restrictions. Photographers automatically own the copyright of their photos and can license them for limited use (in some cases they may pass / sell ownership on to someone else or their estate).
Wikipedia has a photograph of Michael Jackson which I believe you can use in a commercial setting but you must (a) credit the photographer (b) include a link to the licence and (c) not imply the photographer is endorsing your use.
https://en.wikipedia.org/wiki/File:Michael_Jackson_in_1988.jpg
"This file is licensed under the Creative Commons Attribution-Share Alike 2.0 Generic license."
"You are free to:
• Share — copy and redistribute the material in any medium or format for any purpose, even commercially.
• Adapt — remix, transform, and build upon the material for any purpose, even commercially."
You can find out more about what that licence allows you to do here https://creativecommons.org/licenses/by-sa/2.0/deed.en (note that you may not sell the image itself, but can use it in other commercial works).
There are other photos of Michael Jackson on his Wikipedia page, you'd need to click on any that you like the look of and check the licence for each (as they may all be different) and you won't be able to use all of them https://en.wikipedia.org/wiki/Michael_Jackson
Pixabay also has a couple of relevant images - you can use these freely in commercial settings and you don't have to give credit but it's generally a nice thing to do if you can.
Wax figure: https://pixabay.com/photos/michael-jackson-wax-dummy-738410/
Cartoon portrait: https://pixabay.com/vectors/singer-portrait-jackson-musician-7022384/
If there's Michael Jackson memorabilia in a museum near you then if you can take a photograph of that you can use it (you own the copyright), but obviously check if the venue permits photography first. Or find a cartoon of a sparkly glove (that you can use) to make people think of Michael Jackson ;)
Some of the photos on Flickr can also be used commercially (but check the licence of each first) https://www.flickr.com/search/?text=Michael+Jackson&license=4%2C5%2C9%2C10
Venues to sell
Like others Etsy wouldn't have been my first thought, but TES Teaching Resources would be. You can sell stuff there (I don't know what their fees are like though). See also https://www.tes.com/author-academy/getting-started/share-or-sell-your-teaching-resources-tes
Etsy is very international but the fee structure is a bit yikes.
The Council for Subject Associations might be useful too: https://www.subjectassociations.org.uk/our-members/
YouTube links
Yes you can add links to YouTube videos. In your document / PDF you can make sure that these are clickable (copy the address, make sure the same address is selected and Ctrl+K should bring up a box to let you paste the link in to hyperlink, some programs will automatically convert something that looks link-like into a clickable thing).
If teachers are more likely to be only dealing with the thing printed out then you can change the font of the link to Trebuchet MS / Andale Mono or Courier - something that helps make the number 1, lowercase L or capital i a bit clearer so it's easier to type the link in,
It's even better if you create a free Bitly account, create a new short link which points to the YouTube video and change the editable bit of text after bit.ly to be something human readable. Another advantage of Bitly is that you can see how often people have typed in or clicked your link. I would always recommend including the original YouTube link as well though, just in case of problems.
Suggestions
Create a Google Form mailing list
That's free with a Google account and it will automatically capture the information into a Google spreadsheet for you. You could a short Bitly link that points to the form on all your marketing material to encourage people to sign up to hear about your new resources.
Adapt stuff for different printers
I'd also recommend making your items in A4 for the UK audience and then opening a blank document sized for US Letter (8.5 inches by 11 inches) and pasting in the text and tweaking to fit. Up to you if you want to adapt spelling and language for American audiences too.
If possible save your files as PDFs as they tend to open a bit more easily on a variety of platforms. Stuff also needs to be visually appealing to stand out.
Jo