I think need 2 more types airplane:
spy airplane (he can fly on enemy terretori and has a chance to show up 25 to 60% (depending of the level))
transport airplane (can transport light tank (3 lvl) and soldiers (motorized infantry - 2 lvl; mechanized - 3 lvl)
About map:
I think need add rivers and bridges, spies and airplane can destroy bridge.
spy airplane (he can fly on enemy terretori and has a chance to show up 25 to 60% (depending of the level))
transport airplane (can transport light tank (3 lvl) and soldiers (motorized infantry - 2 lvl; mechanized - 3 lvl)
About map:
I think need add rivers and bridges, spies and airplane can destroy bridge.