Looking at the problem from a higher level, there are really two issues: Shoot and move, and initiative * movement.
For the Shoot and Move issue, why not give an initiative bonus if you move and do not attack and/or initiative penalty for doing both in the same turn. This would allow units to rush past blockers easier by moving and not taking time to attack the adjacent blockers so that they can bypass them faster. In the case of kiting, given initiative being equal, the ranged unit will move and shoot, while the melee unit will move and then move again sooner, allowing him to eventually catch the kiter.
That brings up the bigger issue, I think, of initiative multiplying movement. Initiative as a means of allowing you to attack or perform actions faster is fine, but movement gets a de facto multiplication by your initiative in tactical combat. It doesn't in strategic movement, so why does it in tactical? What the solution is, I don't really know because they are so linked at the moment. Initiative affects how often your "turn" comes around, but it should not affect how far you can move in a given amount of time.
The only thing I can think of is a system that replenishes a unit's movement based on the unit's raw movement rate and passage of time. Basically it takes X units of time to replenish your full movement, regardless of how often you can act. When your turn comes up, you can use your available movement and/or act. If you use all of your available movement, depending on how soon your next action comes, you may or may not have your full movement restored. Low initiative units would have most or all of their movement restored by their next action.
Something like this makes combat a bit more interesting for high initiative units. Do you use all your movement to rush the enemy and attack, leaving yourself unable to move far next turn, or do you move close to the enemy, then dart in and attack, then fall back, or rush past next turn?
If a ranged unit does have really high initiative and movement, then he should be able to kite to some degree, otherwise what is the point of building such a unit? The movement * initiative makes this behavior extreme though.
As for high initiative casters destroying the field before anyone else can act, I thought that casting time was supposed to represent an amount of hard time units necessary to cast the spell. Measuring that casing time in unit actions opens the system for abuse as we have all seen, with Blizzard or Fireball being cast by Impulsive casters before anyone can move. If casting time was measured in hard time units and the spell was placed in the queue at that point in time, then at least everyone would get to move before the spell was released.