As for how to identify the tiles in range, there was a question similar to this recently - maybe this will give you a useful starting point?
(Note that those examples assume you want to work with all tiles within a radius. If you want to show walking distances around obstacles, use Depth-First Search from the character's position, returning whenever you hit an obstacle or your search depth reaches your maximum hop count)
For displaying the range with a blue tint, I might try something like...
const WITHIN_RANGE_COLOR : ColorTransform = new ColorTransform(0.5, 0.5, 1, 1);
const NORMAL_COLOR : ColorTransform = new ColorTransform(1, 1, 1, 1);
then each time you find a tile in range, do:
tileDisplayObject.transform.colorTransform = WITHIN_RANGE_COLOR
just don't forget to set it back to NORMAL_COLOR when you're done displaying movement range.