I am looking for a module that would be able to filter events by at least 2 parameters at one time (i.e. Location and Category). Ideally, this module would also need to be able to display multiple custom fields when a user was viewing event information. Also, last but not least, the underlying data behind the module would ideally be able to be easily edited through Microsoft SQL Server Management Studio.

If someone can help me I'll be eternally grateful! (I've spent days looking for this holy grail)

Xmod Calendar integrates very closely with Xmod thereby allowing you to do much of what you've listed. You would not be able to use SSMS with it though as it stores everything in xml. It also has other limitations such as no recurring events.

You could also look at the Events & Registration module - just look under module best seller list in snowcovered.