Passing URL parameter to InfoPath and InfoPath rules timing problem

I had this issue trying to pass a URL parameter to a lookup column in InfoPath. Lookup columns are not available as connection targets from the Query webpart so I had to do some roundabout engineering (quite common with InfoPath).

1. Create a visible field on the form for your incoming parameter (textbox, calculated value, etc). 
2. Create an action rule that fires when the value of this field changes to do whatever you need to get done (set dropdown or other field). 
3. Create a formatting rule that always hides this field.