Create Taxonomy term with added text and date fields, then display them in "add content" I'd like to add a date field ("date") and a text field ("notes") to a taxonomy term ("Category").  Easy enough.

When I add content, I have the taxonomy term linked using term reference, and it is working fine. 

What I can't figure out is this: I'd like the "date" and "notes" field to also appear on the add content screen once the "Category" is selected, and be fully editable.  How would I go about this? 

Specifically, when I add content, I select the category and enter all other relevant data. I then enter a date and notes that apply to that node being created, and also apply to any other node of the same category.

Thank you for help!
Am not familiar with any contributed module which will server your requirement.
But i can help you to achieve this functionality.

Add the Date and Notes field to the specific content type using the 'Add Existing field' option. Since you have already created the fields for taxonomy term, its not necessary to create a new fields.

While adding a new content of that particular content type, mention the category , date and notes in the respective fields. 

Now what we need to do is to hack-into the node submit flow and update the specific taxonomy term with the newly entered date and notes values.

Easily do this by using a single hook : hook_node_presave($node)

You can using this hook in any of the custom module. The '$node' variable will contain the date and notes values. We can easily load the selected taxonomy and update the date and notes of the taxonomy via DB queries

Thanks,
Vineeth