Yes, I would be interested in the answers to these questions too. At the moment I am doing rather cruder adjustments to my mod, such as reducing the Max Chits for Trench Warfare from 4 to 2, except for Germany which can have 3 Chits and starts with Level 1 Tech already done. My idea here is that there should be a reasonable chance of the Western Front being deadlocked between late 1914 and early 1918, so that the other fronts can develop more "historically" than at present. An awful lot is lost from the game if the Western Front has developed into the decisive artillery battle by mid 1915.
In terms of questions 2 and 3 in the second post, I saw the AI attack the same hex of mine with 7 different units in 1 turn! An isolated unit I could accept, but this unit was part of a prepared defensive line.
The other thing I do is cap the highest levels of Trench Tech for each nation. Germany is 5; France, UK, Austria-Hungary, Serbia, Russia, Italy and USA is 4, others are 3.