Blimey Paul, you're unlucky! Is the chip on the windscreen within about 1cm diameter? If so, you can have it fixed virtually invisibly and for free in conjunction with your car insurance. Re: the headlamp, it must have taken a hell of a knock, those things are polycarbonate like the 156, aren't they? Are you sure you can just change the glass, I thought not? Either way, a breakers or ebay would be good if you don't mind the hassle.
Any time my windscreen has been damaged by a stone chip it has been caused by a car travelling in the opposite direction, I know this for a fact because all three times it has happend to me there have been no cars in front of me.
Not saying your case is the same but it shows your speed has no effect on your stonechip luck, or lack of it.