Form Widget Help: Return reference number to the User on submission & dropdown conditions

I have created a simple form to create a new row in an underlying table, which is working fine.

I’d like to enhance the form submission in the following ways, but I don’t know how to implement:

  1. Return reference number to the User on submission: I use the row_id as the reference number and like to inform the user of the row_id of the new record (to be) created either in the form prior to submission or in the submission feedback. I don’t see a post-submission process option or a way to modify the submission response with table data (i.e. the row_id of the new row).
  2. Dropdown Conditions: Dropdown conditions work fine in the underlying data table, but I can’t figure out how they can be coded in the data entry form.
    If I setup each field in the form the same way I did in the underlying table, there is no dropdown condition box to enter the condition, so all values in the column, not just the valid values, are shown in the reference dropdown.
    Also, if I try to enter the table column as the reference source, it is greyed out and not allowed.

If these are not possible in the Form Widget, should I try creating a Custom Widget or something else? If so, can you suggest an example that I could use as a starter?

Thank you.

Can anyone help with me with the Grist Form Widget to:

  1. Return reference number to the User on submission; or
  2. Setup Dropdown Conditions?

TY