
Air warfare is really kind of cool, and yes it is very important - having effective reccee greatly increases the power of your artillery.
I haven't used gas much - I've ben on hte receiving end a few times & I'm not really sure what effect it has!! I did use tanks a couple of times a few builds back, vs the AI, but again I'm not really sure what they did.
City numbers are some measure of importance - not sure exactly what hte mechanics are but if you take a high number city it has a larger effect on morale than if you take a low numbered one.
The number of corps that can be "activated" by spending a HQ point depends on how many corps there are adjacent and stacked with it - there are stacking limits for all hexes - I think open terrain has the highest at 14 points, and 10 points for mountains is the lowest from memory. Infantry corps are worth 3, HQ's 1, artillery 1 or 2, ditto cavalry.
We've got a new build to play with so let the games begin!![8D]
Oh yes - the letters on units refer to their quality - but are not the same for each nationality. So all nationalities get "A", B and C class units, but they have to be really digging into their reserves to get D and E class ones - I've seen them for Serbs and Turks.
However units with hte same letter are not necessarily the same quality - eg Turkish and Austrian "A" class units are almost certainly worse quality than German ones......but we don't really know just how much difference there is!