There is a hill with a palisade on it in front of the Front Gate. When I think of a hill, I think of a big lump in the ground, not a sloping embankment leading up to a wall.
Technically the entire town is on a hill. And there's a hill not far from the winch gate. I wouldn't consider the hill on the back gate an actual hill, more like a slope, or ravine, since you never see the other side.
On Castle it's simple: "meet me at the left side of the castle attackers view".
Because that's easy to type out quickly....especially with the text lag of M&B. I seem to type faster than the game likes to handle and it leaves out letters pretty frequently.
For now, in large battles it should be announced to the team at the beginning that "North" is the direction straight away from the spawn point. Therefore the Barn Gate would become the North Gate to the attackers but the South Gate to the defenders, etc.