Did a comparative play-through of version 1.3, and confirmed that the above issues 8a, 8b, 8d, 8e, 8j, 8k, 8l, 8m, 8n, 8o, 8p are all regressions introduced in version 1.5 as a result of refactoring the Industrial Zone into 4 separate modules to improve the frame rate, and introducing a different ending. As for 8g, version 1.3 includes a separate shader patch to correct the problem.
In other words, most of the problems above (some of them quite serious, resulting in incompletable quests) are not present in version 1.3, therefore version 1.3 is the most stable version of the mod available today. It also has a more interesting and believable ending (IMO).
Since version 1.3 was never hosted on this site for political reasons, and it's not possible to download without buying the game on Steam, this leaves GOG and Retail game owners with either buggy 1.2, or buggy 1.5. For these users, I am hosting version 1.3 on my web site for the time being. Note that the shader patch component (opengl32.dll and the shaders_override folder) are intended for Steam version only and need not be installed for other versions.
http://pa3pyx.dnsalias.org/stuff/m478ep13.7z