A. ALL flowering MJ will stink to high heaven.
B. I'd say no on the insulation.
C. ??
D. Go buy reflective Mylar at a plant store.
E. A fan is used not only to strengthen the stem to hold bud weight, but more importantly to pull more CO2 enriched air into the plant (plants need CO2). ALSO, the air circulation keeps the top of the plant cooler under the light, thus keeping the bulb closer to avoid stretch.

What I'm saying is,.. You need a fan to pull fresh air into the grow space. Without adequate CO2 the plant won't grow very fast, and buds will be very small. the stems will not thicken and strengthen and you'll have to keep the bulbs farther away. So the plant will get tall fast.

So you pull that bolt out, and the machine falls apart.