There are other issues to, such as when a power provokes. For example in the case of the ranger's Nimble Strike, which of the following situations occur:
(a) you start adjacent to an enemy, and since you are using a ranged power, it provokes an OA, even though you shift away from the target before rolling for the attack
(b) you start adjacent to an enemy and shift away, before attacking, and avoid the opportunity attack
(c) you use the power to shift adjacent to an enemy that you weren't adjacent to initially (perhaps to flank) and you trigger an opportunity attack when you make the attack roll
(d) you use the power to shift adjacent to an enemy that you weren't adjacent to initially and do not trigger an opportunity attack when you make the attack roll because you weren't adjacent to the target when you began the ranged attack.
Then there is the sustaining a power question