Hi Jodie,
1. “… only show in admin…”
– For notes to be displayed to admins (and shop managers) only, you need to enable our “WooCommerce > Settings > Product Notes > Private notes” section (i.e. vs “WooCommerce > Settings > Product Notes > Public notes” section).
2. “Can these notes be added individually for variables on variable products?”
– Yes, you can add notes for each variation separately (and for the main variable product as well). I have to mention though – currently, you can add only one note for each variation β we are planning to allow adding multiple notes for each variation (same as it is now with simple (or main variable) products) in one of the next plugin versions.
3. “… how does it display in the admin email?”
– Please check this screenshot that I’ve just added. As you can see, notes are displayed as line items with each product. P.S. To add notes to admin emails, you need to enable the “Admin emails” checkbox in “WooCommerce > Settings > Product Notes > Private notes > Backend Options”.
Hope that helps. And please let me know if you have any questions.