Update. After more troubleshooting i found a combo-box items only generate it's list after it has been opened. A workaround for this is the code below which opens / closes the combo but doesn't take focus. 
 
; --- Find window/control ---
	ConsoleWrite( "--- Find window/control ---" & @CRLF )
	Local $pCondition0
	$oUIAutomation.CreatePropertyCondition( $UIA_AutomationIdPropertyId, "cmbAddressType", $pCondition0 )
	If Not $pCondition0 Then Return ConsoleWrite( "$pCondition0 ERR" & @CRLF )
	ConsoleWrite( "$pCondition0 OK" & @CRLF )
	Local $pComboBox1, $oComboBox1
	$oWindow1.FindFirst( $TreeScope_Descendants, $pCondition0, $pComboBox1 )
	$oComboBox1 = ObjCreateInterface( $pComboBox1, $sIID_IUIAutomationElement, $dtagIUIAutomationElement )
	If Not IsObj( $oComboBox1 ) Then Return ConsoleWrite( "$oComboBox1 ERR" & @CRLF )
	ConsoleWrite( "$oComboBox1 OK" & @CRLF )
	Local $pInvoke, $oInvoke
	$oComboBox1.GetCurrentPattern( $UIA_LegacyIAccessiblePatternId, $pInvoke)
	$oInvoke = ObjCreateInterface( $pInvoke, $sIID_IUIAutomationLegacyIAccessiblePattern, $dtagIUIAutomationLegacyIAccessiblePattern )
	If Not IsObj( $oInvoke ) Then Return ConsoleWrite( "$oInvoke ERR" & @CRLF )
	ConsoleWrite( "$oInvoke OK" & @CRLF )
	$oInvoke.DoDefaultAction()
	$oInvoke.DoDefaultAction()
	I also found using the Legacy Select lets me select my item without taking focus. I don't know why it needed the number 3 but without it didn't work ^^. 
 
	;Find List Item
    Local $pCondition4
	$oUIAutomation.CreatePropertyCondition( $UIA_NamePropertyId, "Do it later", $pCondition4 )
	If Not $pCondition4 Then Return ConsoleWrite( "$pCondition4 ERR" & @CRLF )
	ConsoleWrite( "$pCondition4 OK" & @CRLF )
	Local $pListItem1, $oListItem1
	$oComboBox1.FindFirst( $TreeScope_Children, $pCondition4, $pListItem1 )
	$oListItem1 = ObjCreateInterface( $pListItem1, $sIID_IUIAutomationElement, $dtagIUIAutomationElement )
	If Not IsObj( $oListItem1 ) Then Return ConsoleWrite( "$oListItem1 ERR" & @CRLF )
	ConsoleWrite( "$oListItem1 OK" & @CRLF )
	Local $pInvoke, $oInvoke
	$oListItem1.GetCurrentPattern( $UIA_LegacyIAccessiblePatternId, $pInvoke)
	$oInvoke = ObjCreateInterface( $pInvoke, $sIID_IUIAutomationLegacyIAccessiblePattern, $dtagIUIAutomationLegacyIAccessiblePattern )
	If Not IsObj( $oInvoke ) Then Return ConsoleWrite( "$oInvoke ERR" & @CRLF )
	ConsoleWrite( "$oInvoke OK" & @CRLF )
	$oInvoke.Select(3)
	 
 
	One random question!  Can IUI enable/disable controls similar to ControlEnable/ControlDisable?