we have been playing that infantry, armor, artillery and other ground units cannot shoot down any air units, they can only combat other ground units. my original question would be to question whether this is correct or not, and how to fix it. can infantry attack a terr. containing only airunits? can they roll defense against only air units? are there any spec.'s on which units can or cant hit which other ones
That is incorrect. See my above post. Fix it by allowing units to hit what they are allowed to hit.
(if fighters combat a country with other planes and infantry do you roll for air units 1st? or all at the same , then can he can choose infantry as cushion for my fire as opposed to taking out the planes?)
Yup. Defender always chooses the casualties, so will likely choose to sacrifice Infantry instead of his more valuable planes. Attacker rolls all of his attack dice and counts total number of hits, then the defender can choose how to disperse those hits amongst his defending units.
another question about air units. when counting movement in regards to coastal territories: when leaving or landing on a coastal territory do you count the sea zone outside of the country as part of the country itself, in that you only have to reach that sea zone to land safley on the shore?
The sea-zone and the territory are separate areas. Every time you cross a line between a territory/seazone and another territory/seazone, it uses up 1 point of a plane’s movement point allowance. Your fighter must be in a territory to land in it, not next to it.
~Josh