Official plaintext versions of the Creative Commons licenses are available. Are there similarly official Markdown versions?
Many licenses require that the licensed work is accompanies by a copy of the license, e.g. GPL, MIT, BSD, GFDL, …. A Markdown version that can be copied into the project documentation can then be helpful.
However, the CC licenses can be satisfied by linking to the full terms, or even only mentioning the abbreviated name for the license (like CC-BY-SA 3.0). A Markdown version that can be copied into projects is therefore not as necessary, and is not provided.
I don't believe it's official, but they do exist at https://github.com/idleberg/Creative-Commons-Markdown/. It seems well maintained, at least at the time of this writing.
They welcome changes so if anything looks wrong, report it.
No. Creative Commons do not host a Markdown version of their licenses.
The license terms do not require that you distribute a copy of the license. If you want to distribute an official copy anyway, use the plain text version.
This is the wrong place to ask about this, as you specifically ask about official (presumably legally binding/checked for accuracy) versions. Any questions of that nature should be placed at the official channels for the license(s) in question (they FAQs, or any contacts provided for legal matters).