I don't believe Diethylstilbestrol will cause hot flushes, and if you stay on Zoladex too (not clear from what you say if you will or not), I think the Diethylstilbestrol will stop the hot flushes Zoladex causes, but I don't know how quickly that will happen. It should also stop progression of osteoporosis.
These are side effects from the loss of estrogens, which in men are manufactured from testosterone, and hence also lost when on ADT. Diethylstilbestrol will compensate for the loss of estrogens, and should reverse these side effects.
Chris, I hope this works well for you.