If you are just starting to flower, I'm not sure how much leaf drop you should be seeing. I don't grow MJ outside, so I'm unsure of how an outside plant behaves at this stage. For an indoor grow, you don't want to be seeing much leaf drop or discoloration at the start of flowering.

The spray damage. Is it only to a few leaves, or the entire plant? And is the damage staying the same or getting worse?