For the dry start, you can do whatever. More is generally better, up until the point where the leaves start to get burned/dried out. During dry start of my tank, I had ~75w over the tank. When you flood, switch to something lower. You can use the 14w, but def raise it a couple inches above the surface somehow.
What will happen if I let it sit in the top of my tank?
Will it melt the Saran wrap?