Re: Black suits, black hats, white shirts --
I asked a Chabad Rabbi this same question: "Why do they dress in that style of clothing?" "There is no Scriptural basis for it, and ancient Jews certainly did not dress in that apparel!"
He replied that such clothing was the style of the Polish Nobility during the times in which Chasidism was appearing. The Jews wanted to be elegantly but simply dressed, and the plain black and white color motif was to represent humbleness in appearance, etc. .
I personally find that all who dress like this that I have met have the deeply held belief that all male Jews MUST dress and appear like this, or they are not Jews, and seem to become quite emotionally upset over the possibility that Jews would choose any other clothing styles.
I have yet to see an artistic representation of Moses or King David wearing black lace up shoes, black fedoras, white shirt, black pants, and black coats. The truth is the Jews of ancient Israel probably more resembled the Taliban in their style of dress than they did the Haredim: headcovering or turban like wrap, loose fitting gown style clothing, sandals, etc. However, I don't recall depictions of ancient Jews all walking around wearing curved daggers or long swords, other than in time of war.
Of course, ancient Jews always wore Timex brand wristwatches.
Because the Jew, like a Timex , "takes a licking, and keeps on ticking!"