Hello...
Some, may know but I don't think they would be willing to give away trade secrets. Without knowing what the base textures look like (before converting to a DDS file) we could only speculate what they did and how. I'm not asking you to show what Aerosoft did, especially in a open forum. If you like, Teo... Send an example of YOUR textures to me. Just ask through a PM here for my email.
In the mean while though.... AO maps can be tricky because depending on the FS you are creating scenery for, they could look funny considering the shadows would not change with the position of the sun. The base textures that you have though should be from a picture of the building you are are modeling for (realism). If you only have pictures to look upon and recreate by means of artistic interpretation, then the process can be long and hard, especially if you are not sure what material was used to begin with or what height differences in the wall itself. Unfortunately, artistic interpretation can't be taught.
The Principle of the uv unwrap depends on the structure to start of with, but.... since AO maps are not a map in which is used directly (having its own slot), best to have it as a layer within the diffuse texture and with the blend mode changed for that specific layer within your Photo Editor (which can vary also). There is a tutorial in "Creating AO Maps (and Height Maps)" within the Resource section here (but I have updated it, but haven't release it yet - proof reading

). The section at the end of the tutorial explains what needs to be done in blending (with the different modes) the layers.
I hope that helps (at least some of your questions)