[quote=Marco Kalter]We have not yet been able to find a method to determine from the plan_table column contents that a step is inactive. [/quote]
Check the Analyze R12c CBO features from OTHER_XML of V$SQL_PLAN section. You can use the skp attribute from the other_xml column.

And please do ask for help for the other problems, too if you're interested in fixing them. It's not a shame.