A: It’s included in the full firmware package (recovery.img). You can flash it separately via SP Flash Tool.
If this device was indeed distributed by Airis (likely for the educational market in Spain/Europe), the firmware is likely a "de-Googled" or custom-skinned version of Android tailored for schools.
The device gets stuck on the logo screen, continuously restarts, or shows an “error: no valid operating system” message.
A: No. Even other Airis models have different drivers. Cross-flashing will result in a brick.
Due to the obscurity of the Airis Kira N9000, firmware is unlikely to be directly downloadable. Your best bet is extracting it from a working unit or searching Russian/Chinese forums with the exact build number from Settings > About Tablet.
If you have the device’s build.prop or a boot splash image, that could help narrow down the chipset and compatible generic firmware.