How to I properly get a webhook to fire for AddRecord?

The help is pretty thin, I agree.  The best examples are in the API help under a particular API call where they give examples.

here is the API guide

http://help.quickbase.com/user-assistance/Default.html#apicalls.html

here, for example is the example for API_AddRecord

<qdbapi>
   <udata>mydata</udata>
   <ticket>auth_ticket</ticket>
   <apptoken>app_token</apptoken>
   <field name="event_name">party at Lindisfarne</field>
   <field name="description">dress in style of the epoch</field>
   <field name="location">lindisfarne island</field>
   <field name="start_time">06-08-0793</field>
   <field name="end_time">10-14-1066</field>
</qdbapi>

Example Using Field IDs

<qdbapi>
<udata>mydata</udata>
<ticket>auth_ticket</ticket>
<apptoken>app_token</apptoken>
<field fid="8";>party at Lindisfarne</field>
<field fid="9">dress in style of the epoch</field>
<field fid="10">lindisfarne island</field>
<field fid="11">06-08-0793</field>
<field fid="12">10-14-1066</field>
</qdbapi>


So best I can figure you do not need that <udata> line
You do not need <ticket>
but you do need the <usertoken> which is not documented there.