Using iMIS REST API to Update Event Fields (Ideally by Event Code)

I'm attempting to use PHP CURL to update primary fields (specifically directions and notes) for an event in iMIS through the REST API, but I'm encountering several challenges due to limited documentation.

Specific Issues:

Querying by Event Code: I need to query events by Event Code rather than iMIS ID. I understand I might need to create an IQA, but I'm unsure which entity/table this IQA should query against.
Endpoint Structure: I'm uncertain about the correct URL endpoint structure. Is it something like https://{domain}/api/Event/{id} or is there a way to query directly using the Event Code?
Update Process: Once I locate the correct event, what's the proper format for the PATCH/PUT request to update only the directions and notes fields?

What I've Tried:
I've explored the available documentation but haven't found clear examples for this specific use case. Any sample code that demonstrates how to:

Retrieve an event by Event Code
Or alternatively, how to first get the iMIS ID from an Event Code and then Update specific fields for that event would be extremely helpful.

Thank you in advance for your assistance!