You can use an unlimited number of domain names. You can add new domain names in the hosting control panel.
You can manage mailboxes for your domain name via the hosting control panel.
Yes, you can. Scripts can be added and edited using the file manager.
To undo the changes, use Undo and Redo buttons in the website builder panel. If you need to restore the latest version of the website, you can use a backup.
In the website editor, go to the Settings menu (top right corner) → the Scripts section. Insert Yandex.Metrica code in full in the field Before </head>
<!-- Yandex.Metriсa counter -->
…
<!-- /Yandex.Metriсa counter -->
Apply the changes and publish the website to put them into effect. The code will be added to all website pages.
In the website editor, go to the Settings menu (top right corner) → the Scripts section. Add the code line in the Before </head> field. Normally, the confirmation code is as follows:
<meta name="yandex-verification" content="your ID in Yandex system" />
or
<meta name="google-site-verification" content="your ID in Google system"/>
Apply the changes and publish the website to put them into effect.