Here is the order or priority:
https://learn.microsoft.com/en-us/microsoft-365/security/office-365-security/how-policies-and-protections-are-combined?view=o365-worldwide
For the second question, spam notifications will include items in the quarantine:
https://learn.microsoft.com/en-us/microsoft-365/security/office-365-security/use-spam-notifications-to-release-and-report-quarantined-messages?view=o365-worldwide
Note: