I used this article as a reference:
there is a downloadable demo with open source code package at last page, I got the idea and code snippet of the array based pseudo linked list approach of A* from here, which is finally faster than a pure linked list A* (the usual approach), and my old array based A* approach.
Its vehicle movement system was ported to Company of Heroes 1 (Adding Realistic Turn section). I do not use it as I have simple ancient/medieval warfare stuff only with a more simple approach.
you grid array system is really up to you, it is better to store grid location in units, and all important actors. then by running through them you can update the position map(s). I use static, stationary, and dynamic map arrays, depending on their update frequency. dynamic should be avoided if possible. changing the grid structure runtime is not really a good choice, especially array reallocation should be avoided runtime!