Check out the answers to all your queries:
1. Uploading .pst Files from Outlook 2010:
To upload from Outlook 2010 to Office 365, use Microsoft's inbuilt tool. You can either use the Microsoft 365 Import Service or the Outlook Import/Export wizard. These tools will help you smoothly move your emails, contacts, and calendar events to your new Microsoft 365 account.
2. Getting Licenses:
For Microsoft 365, each user needs a license and Microsoft offers various plans with different features. The number of licenses required is dependent on how many users are there to shift the emails.
3. About Azure:
Focus on Office 365 subscription as of now. For a simple move, you don't need another account. If you need additional features you might need Azure. Consider Azure if it aligns with your organization's specific needs.
4. MX Record Change:
IT or domain admins are responsible for managing or changing the MX records. Teamwork here is a must for a smooth email migration.
Need more help? Check Microsoft's guide: https://learn.microsoft.com/en-us/purview/importing-pst-files-to-office-365