Explanation
Graphical user interface, text, application Description automatically generated

Box 1: Yes
The Adaptive Cards Designer provides a drag-and-drop experience to quickly build and tweak adaptive cards.
Outlook Actionable Messages cards are designed using the Adaptive Card format. The Adaptive Card format is a simple yet powerful declarative layout format that provides a lot of flexibility, allowing for visually rich cards. In this topic we'll cover the Outlook-specific features of the Adaptive Card format.
Box 2: Yes
The actionable message card is in JSON format.
Box 3: No
By default, the Tenant Administrator can create, edit, clone, and delete tenants, and manage user accounts.
Note:
To enable Actionable Messages the recipient of the task must be an Office 365 customer with permissions for the SharePoint online site.
No: Office 365 administrators can disable actionable messages via the Set-OrganizationConfig cmdlet. If actionable messages do not render, check with your administrator to make sure the feature is enabled in your organization.
Adaptive Cards Designer Microsoft outlook actionable messages
References: https://docs.microsoft.com/en-us/outlook/actionable-messages/adaptive-card
https://gingkoapp.com/create-tenant-administrator.html