I want to add checkbox that must be activate to send the form, but I've got some problems.
How can I change these words?
To fix the check box, try toggling the check box on and off, saving your form, and re-publishing. As for the text on those two fields, you might want to remove those and use two short text box fields instead. That should let you use whatever text you want for the labels.
Yes First and last name, but I think it doesn't matter when I want to remove it and change this "0" to another text
You won't be able to change those labels with the name element, so you should remove that from your form and use two short text box elements instead. You'll be able to use whatever text you want with those.
Toggling off the cookie opt-in option and toggling it back on should fix that 0 text as well, I think.