All applicable rights are detailed under the terms of GPL-2.0. If there is a specific right or group of rights you're concerned about, feel free to provide specifics.

Yes, you can use your own domain name.

While editing a page, at the top right of the editor switch the from Visual to Text, and you can edit HTML of the page directly.

Please provide some background information such as the theme you're using and any steps we might be able to follow to replicate the issue.

You can check to see if the page is still in your trash. From there, it can be restored. If not, the page might be recoverable only if you took a backup of your site. If you don't have a backup, it's possible your web host does.

Usually, this error is caused by a glitch. If you try running the updates again, it should correct itself. If not, you may want to consider submitting a support request from within BoldGrid Central > Manage My Account > Support Request. 

The "Call to Action" that comes with the Hydra theme is a visual editor widget. You should be able to access it from the Widgets section of the Customizer unless, perhaps, it was already removed?

There is no way to add sticky behavior to a menu from the Customizer. However, we'd encourage you to submit a feature request for it if that is something you'd like to see in a later version.

Also, since the BoldGrid themes are basically WordPress themes, they can be augmented via the child theme system. Alternatively, you could use browser tools to identify the CSS selectors necessary to add a sticky navbar effect.

To remove the background image, go into the Customizer > Choose Background > Remove. For the space, you can remove the default Call to Action (Visual Editor) widget.

This depends on the theme. The "Hyrdra" and "Evolv" themes come with a sticky navigation menu in the header by default.