Am I right that:
Copyleft is not equal to Creative Commons (CC BY-NC-SA "This license lets others remix, adapt, and build upon your work non-commercially, as long as they credit you and license their new creations under the identical terms.") and such copyleft licenses as GPL allows commercial use somehow?
Creative commons license gives rights among others to sell modificated code?
Is the GPL copyleft and doesn't bar commercial use in future versions? The GPL is a copyleft license, as far as I know. But it allows us to commercialize future code modifications without author notification, as I understood it: "A “contributor” is a copyright holder who authorizes use under this License of the Program or a work on which the Program is based. The work thus licensed is called the contributor's “contributor version”.