These are Lithium Ion batteries, 18mm in diameter, 65mm in length
No, these batteries are compatible with any of our lights that accept cradled 18650 batteries, such as the Lumify fairy lights.
Sorry, you'd need to check with vidio as it's not one of our products.
These batteries have internal protection so are unlikely to work with your "project"
Yes, these batteries have internal protection.
This is a single battery.