One thing I wouldnt transplant the plant right during the flowering stage. It would add a lot of undue stress at such a crucial time. Not sure about the soil, but your lighting would be good enough I am sure. Once you switch to the HPS just put the fluros you used more towards the bottom to give the fan leaves light. Also dont use aluminum foil to line the walls. White painted walls will actually reflect more light and they wont heat up like the foil will.