Questions + chief: do I need a checkbox?

Question

User interface

Hello, I opened the article and it became interesting to me:

here is such a clipping from the article (my arrows).
Shed light. At the moment, I think that the form is stuffed with whistles. I want to understand.
Questions:
1) Why is this checkbox needed? why not just replace it with the text Show/hide password? Why not remove it in the input itself? This type makes the interface available? What exactly then? Explain. What happens when changing language? Where will the test with the checkbox go?
2) Well, why are these red stars everywhere? Why couldn't the button be pushed? So wouldn't it be better? Would someone get hurt? Explain what is the point of making stars on 3 fields when you can block the button?
3) Why gray locks for signatures? Is this some kind of psychological trick? What will change if we remove them? Will the user get scared and will not fill out the form, feeling unprotected and deceived? What is justified in your opinion?
4) An additional question: are checkboxes needed, for example, in application forms? Why not write simply and briefly before the button: I agree with the rules of the site. Is the checkbox required?
Enlightenment :3

Answer 1

1. In general, a matter of taste. You can do it the way it was done, and the way you suggested. There is no significant difference.
2. When the entire button is disabled, it is less visible to the user. Let's say we have a password requirement - for example, at least 8 characters. He entered 7 and filled in all other fields. And the button is still not pressed. What is the trouble, the user thinks? And he sits and wonders what he did wrong. It is better to let him make a mistake (press the submit button of an incorrectly completed form) and then clearly show where he is wrong and why.
3. Cosmetics, gives +10 to the user's sense of calm :)
4. Sometimes you need the user to consciously agree with the rules. If you leave the text "I agree with the rules", then not everyone will even notice it.