Any plan that includes the SharePoint service. For Enterprise plans: E1, E3, or E5. For Small Business: Business Premium or Business Essentials. For Education plans: A1, A3 or A5.
Every user with Office 365 license that includes SharePoint
Both. Helpdesk can be configured to work as a Helpdesk solution for your own employees, your own customers, or a combination of the two.
It’s a user with access to Helpdesk who doesn’t have an office 365 license, such as your vendors, customers, partners, auditors, … etc.
It is free. You can set-up as many external users as you require as they are excluded from Microsoft licensing.
You sure can! you can download a 30 day trial version of Helpdesk for free by clicking this link here.
Bank transfers or checks.