Inkpad X

I'm considering the Inkpad X, since my beloved Kindle DX is slowly dying...

Can I ask a few questions?

1) are you satisfied with the device?
2) is a cover/sleeve included? I cannot understand it from the amazon link https://www.amazon.it/gp/product/B07...PNWYJU7H&psc=1
3) there is the possibility to have subfolders? I'm used to store my books in different folders, named by the author
4) is Calibre working OK with it?

thanks!