Should you crush the sugar crystals (to promote rapid cooling) or should you use the largest possible crystals so there are more bonds to be broken?

I'm going to guess that there's a sweet spot in there somewhere; a priori it seems you want the maximum size that will dissolve completely.

If I remember the answer correctly, it went something like this. Dump all sugar into the tea at once and wait for the temperature to settle. Now split sugar in two halves, dissolve first half, wait for the temperature to stabilize, dissolve second half. Through math it worked out that the second method cooled the tea more. So the answer was to go with the infinitely small pieces of sugar :)