Q1.
At:
https://www.kali.org/get-kali/#kali-installer-images
says:
"Kali is a rolling Linux distribution,..."
What that means? is it Debian Linux derivative?

Q2.
Every when Kali Linux is updating their installing ISOs, VM prebuilt images, etc...?

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Installer Images

Kali is a rolling Linux distribution, meaning as soon as we have an update, we ship it. Would-be users have a variety of images to choose from. For more information, please see Which Image Should I Download? and Kali Branches. For most users, we recommend the latest ?point release? image below, except in cases when a user requires a specific bug patch, in which case the weekly build may be best.
We generate fresh Kali Linux image files every quarter. These become the official "point" releases. These images are tested and subsequently announced with a blog post.
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