Hi!
Following your link I found a list of books, but none of them is covering 3dGS in a specific way. Or maybe I didn´t see. 3dGS should not be confused with 3d Studio Max, which is a modelling application. I only know of one older book, which might be a little bit out of date.

When I started with Game Studio, I downloaded the manual (link on the download page), which gave me a good overview of the actual possibilities. There are also some basic essential tutorials (c-script workshop, level design tutorial). You can also have a look into the AUM (user magazine).

A7 will come out this year, but 3dGS is constantly being updated, so A7 won´t be something completely different. It´s more a gradual change.
Most important for me: in the past the engine was mostly designed for indoor BSP levels. It´s gradually changing into something that can handle larger outdoor levels (with lot´s of visible models, improved dynamic lighting, large terrain etc.). In addition to that it will be more comfortable to artists and level designers (shader library/editor, interactive leveleditor).