i am not sure I undertand 2nd paragraph. Regarding 1st one: I don't think there's "best" balance. It really depends on what type of game you want.  I think you can automate a lot things and still have good game. For example , (extreme) example: you have FreeCiv/Cilization or Heroes of Might and Magic 3 games - you don't have micro and APM requirement at all there, but it's still good game. It's extreme example, but you get point.  Thing is, if you remove mechanical requirements, you need to add complexity elsewhere. HoMM has many resources, upgrades, location and possible decisions. FreeCiv has many tech paths, city improvements, units, etc. Mechanics doesn't help there. You need to read and learn a lot there.  For 0AD, I really think we need to constantly look at AOE 2 but keep 0AD unique and not just bad copy of that game. But those fundamentals need to be taken into consideration.  Also overall 0AD players skills are lower then AOE 2 - so it's good to keep that on mind and make sure it's not too APM demanding. With time, as players' skills progress, you will need to switch more towards mechanical demanding game to make sure top players are not bored. 

forum these past few days: 20% other things, 80% auto train argument

Yes,  existed in A26

Please do. My honour!

The result is tolerance of macro mistakes.  If this feature gets in, all I have to do in the first 10 minutes of the game is set my CC and Barracks to produce certain batches of units, set Auto-train to ON and never touch those buildings again until I get to the City phase to unlock champions. I don't know about you, but this simply awards laziness and kills the fun of actually managing your production.