Wow, like any of us would spend countless hours trying to match of your aerial photograph to your exact piece of property that you want help with in deciding how you should set up your range. While nobody asked for you, you just thought the teaser would be nice to let us know it is available, but we can't see it?
Let's see, you want to shoot longways, but there are houses a couple thousand feet from the far end, so they would be behind your backstop, right? You aren't willing to move the house toward the far end and shoot back the other way? That seems like the simple safe solution, but then again, you didn't tell us if there were houses in the other direction and we don't have the aerial photographs to see for ourselves.
As you described it, there are two directions of fire, parallel to the road and toward your neighbors and perpendicular to the road on a very short axis. Well have you considered shooting at a diagonal?
Out of what should the berm be constructed? You have been to gun ranges, right? What are the berms usually created from? Dirt. It is cheap as a construction material can be, very plastic in being able to adapt it to particular circumstances, provides deadblow absorptive impacts primarily, does not require engineering skills to create, provides some noise absorption compared to materials such as rock, and you probably already have some on the property right now.
How high should it be? Considering your concern for your neighbors, it should be as high as you can afford to make it. If you can't afford to make it very high, then make sure your targets are low. If your firing elevation is superior to the elevation of the impact location, then your shots will be in a trajectory that assures that missed shots are grounded or bermed. If the target is superior to your firing position, missing shots will have a greater likelihood of sailing over the berm unencumbered.
Given the distance to your neighbors and your concern in shooting their direction, you might want to consider only using pistol ammo and ideally powered down target loads.
Of course, you could just spend the money and buy the NRA book on gun ranges. It has a LOT of very good information, suggested berm heights, materials, use of baffles, etc.