[the total time from when the aircraft first moves under its own power for the purpose of taking-off until the moment at which it comes to rest after landing.
It is pretty self explanatory.
Don't ask the people here on this forum - just look up the CASA website for the legalities.
As for being PIC just for a ground run - well, you have to take responsibility for the aircraft whether you intend to go flying or not. That's why we all spent so much money to get our licences in the first place.
