The deathtouch keyword works only when damage is assigned, so first strike can beat it when the creature is destroyed during the first damage step
Whenever Grasping Giant becomes blocked by a creature, exile that creature until Grasping Giant leaves the battlefield
Dig Through Time provided you with the same amount of raw cards as Divination, but they would often be two very good cards
From a historical standpoint, I believe Chandra, Pyromaster was the next solid attempt, helped most of all by the creation of impulsive draw
I think its extremely fun to play, and it puts its focus on a relatively out-of-the-box style of play (even if by this point its one of the most popular archetypes)
With that in mind, lets look at all the best Jeskai commanders, and how to better choose your tools for the job