Is that the same plant that has those weird round leaves? I would look into getting seeds and possibly selling them to a breeder in holland, since who wouldn't want to grow a marijuana plant that didn't look like one? I don't know if you've ever grown cuttings before, but that might not be a bad idea.

As for the shed, the only real way you can tell how hot it'll get is by putting a thermometer out there in the hottest part of the day. If you're concerned about heat from the light, you can make the night cycle happen during the hot part of the day.