The idea is
a) to allow an outnumbered country to hold a turn or two longer
b) add extra units(helis) that are a sort of an Amphibian for extremely mixed terrain(water+forest+desert+rifts) they are fast, but untransportable.

2handed units are more single-player wise, but have thier uses too - they are powerfull and allow you to concentrate fire in a narrow place.

there are also few auxilary units that have to be balanced to fit the designated role.

Yes, i think that pillboxes and helicopters will *greatly* change a gameplay. It is not case for other new units.

But it is not known yet, what is Super Weapon for two sides...