Hello Michael,
Welcome to the Microsoft Q&A and thank you for posting your questions here.
I understand that you would like to know who has access to Developer Support from your Azure instance.
Regarding your specific questions:
Who can submit support requests?
Users with Owner, Contributor, or Support Request Contributor roles at the subscription level -https://learn.microsoft.com/en-us/azure/azure-portal/supportability/how-to-manage-azure-support-request.
How to check who has access?
Use Microsoft Entra Admin Center to audit role assignments - https://learn.microsoft.com/en-us/entra/identity/role-based-access-control/permissions-reference.
Does Developer Support include Q&A?
No. Microsoft Q&A is public and not tied to Developer Support
Does it cover Visual Studio support?
Only for Azure-related development (e.g., App Services, SDKs) - https://azure.microsoft.com/en-us/support/plans/developer/ and https://learn.microsoft.com/en-us/visualstudio/azure/overview?view=vs-2022
Limitations?
Severity C only, business hours, no proactive guidance - https://azure.microsoft.com/en-us/support/plans/
I hope this is helpful! Do not hesitate to let me know if you have any other questions or clarifications.
Please don't forget to close up the thread here by upvoting and accept it as an answer if it is helpful.