Slitherine

Gents,
please help me with following:
a) is there a way to see unit's experience in a number (just like in PzC)? I see starts, but have to idea how fast the unit is progressing
b) how can I learn what is 'big air', 'small air'? Fighters description says 'some fighters are dog-fighters, some are interceptors' - how do I know what is what?
c) any way to read enemy unit stat in details? It is only possible to see its stat while holding a mouse on it, but I'd like to open it in separate screen to read what each icon means.

Upgrade:
In comparison to PzC, I find upgrade ridiculously expensive even withing the same class - i.e. upgrading infantry within its class costs ~75% of a new unit cost. Any hints on how you handle upgrades? I see no point in disbanding units - it pays peanuts - I'd rather deploy and KIA them.

a) The game shows the exact experience amount as a tooltip if you mouse over the experience bar.

b) Each air unit's defense type is listed as either 'LARGE' or 'SMALL' at the bottom of the unit's statistics sheet. This determines which of their two corresponding attack statistics, 'Attack against [Air] Large' and 'Attack against [Air] Small', units firing at that unit will use in combat.