How safe is a current transformer
There are two ways to get a shock from such a setup:


Connecting to the live circuit. This is unlikely as there would have to be insulation breakdown of the live conductor, the CT and the CT wire insulation.
A shock from high voltage generated by the CT during measurement. Theoretically this is possible on an open-circuit CT when significant current is flowing in the primary. In practice it doesn't seem to be much of a problem in small CTs. To get a shock you would need to touch both terminals simultaneously. The shock current would flow from terminal to terminal through your body and not to ground (through your feet mentioned in the question).



  Is it safe to touch all the connectors of the audio jack, with my feet touching the ground and the mini-CT attached around an AC live wire that's currently drawing a current? 


Bare feet? No, not safe for any work near mains. You should be wearing decent work shoes.