In your case, that's not the renderer settings. Who do you work with the most important stage and the concept of its lighting.
So in order
Why windows is not realistic?
Yes, because they do not really realistic at Wash models. You basically do not have windows, you have a mirror. Window to become the window glass in it must be transparent or translucent. Then they will be the volume. Even if the inside of your building shell is nothing there, still, the glass should not be mirrored, they must transmit light into the building. Just do the floors and floors through windows would have viewed the building depth. In addition, the glass model should also be thick, otherwise there will be problems with refraction.
What is lacking in the shadows?
Shadows strongly dense and crisp. That is, the shadow is very dark and has clear boundaries. Often, it does not look realistic. To get rid of the need to lighten the shadows, raising the global brightness of heavenly light and slightly blurred shadows in the light settings. You should experiment a bit and you are sure to find the right balance between the brightness and shadow density.
Why reflection dim?
Because as a reflection source (of which should be reflected) you vulgaris 8u or given a 16 bit raster map (on the hemisphere with VRayLightMtl). However, this is not a realistic situation, because the LDR image has a very small range of brightness, at the same time as in the real world, the difference in brightness, for example, the heavenly light and the trees standing on the ground - is huge. Do you they are almost the same, ie, the brightness of the surrounding objects is comparable to the brightness of light sources. It's not natural. To make a realistic reflection, you need to raise the dynamic range of the surrounding environment, using as a picture of the sky and clouds HDR image .
What is "okkolyuziya"?
In fact, I have no idea what meant the one who wrote it on the Internet, but I can assume that it was about Ambient occlusion in the context of post-processing. For you to understand what it is, I suggest you read our mini splint on Ambient occlusion (AO) and its application . Its relevance in your scene, I think, you yourself make a conclusion
No, HDR cards are used for reflections and lighting, for the same hemisphere with clouds card on it - covers the whole scene as it applied luminous VRayLightMtl.
If you do not invest VRayLightMtl * .jpg card and VRayHDRI map , with the corresponding HDRI map in it, then your scene will already cover the HDR map.
Regarding the method with self-luminous hemisphere, it is rather a matter of taste, because the 3ds Max Environment Map (key 8 on the keypad), it's just a sphere at infinity from the center of the scene, but in fact it is the same self-luminous area (not a hemisphere, and the area ) with a texture stretched over it.
The difference between the luminescence and luminescence Environment Map sphere / hemisphere over the entire scene, as soon as that in the first case, the scope of vyuporte not visible, but it only appears during rendering, thus not interfering with the objects in the scene.
In addition, it makes sense to cover and are reflected in the rendering using HDR cards, or any other way, but after the final rendering, replace the cloud at all renderers - in Photoshop. That is, using the postprocessing rendering , replace dull or not very suitable sky on a beautiful and bright.