| mdt |
The mount counts as an ally if it has the feat. Most mounts can't qualify for the feats, since they don't have intelligence. This means a cavalier can't grant feats to his mount unless it's sentient.
You are adjacent to the mount you are riding. The mount takes up the five foot spaces it takes up, and you take up a five foot space above it. You are therefore adjacent (in the z axis, not the x/y axis).