1. Great!
Thanks for your suggestion.
I will share your suggestion with our developer team.

2. These pages are only for the presentation.
We have created these pages to present our theme functionality and features.
But I will share your point with our developers and maybe we will put it in our future plan to add these pages for dummy data.

3. This newsletter form is the default form of the Mailpoet plugin.
Please delete this form and create your own form on the following path :

Dashboard > Mailpoet > Forms

Then add this newsletter form created for the Mailpoet widget.

Also, you can change the label display on the following path :

Dashboard > Mailpoet > Forms > Edit one of the form > Edit field settings

Best Regards.