@Sigma:
Hallo from Germany
Hello and welcome!
@Sigma:
1.)
If a fighter attack with ground units an abut enemy territory, would he attack each round, or only the frist round and fly back?
The fighter attacks each round, just like the ground units.
@Sigma:
2.)
Are ground units allowed to fire at air units, witch are attacking them? (fighters and Bombers?)
Yes, ground units can hit air or ground units. Ex. if a bomber attacks an infantry, the bomber would have to roll a 4 or less to hit the infantry, but the infantry returns fire and on a 2 or less would kill the bomber.
@Sigma:
3.)
If a bomber fly over enemy territory with enemy fighter, can these fighter attack the bomber? Or could only the flak attack?
Only the flak would fire if the bomber flies through the territory. If the bomber is ATTACKING the territory then all units in the territory would defend.
@Sigma:
4.) Are casualities of opening fire allowed to fire back, or they destroyed immediately?
If by opening fire you mean flak or battleship bombardments, then they are destroyed immediately with no chance of return fire.