I never bother with the wyeast/white labs temp guides, and almost always go a few degrees below suggested range. That said, you didn't ferment too high but I think you will find more balance between the flavored if you start out as little lower.
I don't think you over pitched, but if the starter was too small or you did not provide adequate aeration/nutrients you could have done some damage to the population. A 1L starter may be too small unless you are constant agitation/aeration.
When I brew hefeweizens I usually make a 1L starter and hit with pure 02 and some nutrients and pitch during high krausen. That's my preferred method, or I pitch 2 packs/vials per 5 gallons of wort.
That said, I've had similar problems with this strain and found that adding copper to BK and nutrient helped clear up the sulfur. I can't remember exactly but I remember wheat malt may be deficient in some nutrient. Someone correct me if I'm wrong.