Q1. What occurs after 5 superficial hits take place?
A1. After five superficial hits you have visible external damage. (see 7.39 Successive Attacks.) That means that even if your ship has no serious damage, it still has taken so much damage that it looks seriously damaged to the enemy fighters and they will single out your bomber and try to bring it down.
Q2. Is there a flak check in zone 1 due to navigation (if it occurs)? It seems that zone 1, being so close to Britain, a flak check would be unrealistic. Is there a possibility to make an exception to exclude flak checks in zone 1 ?
A2. No, no flak check in Zone 1 (even if it sometimes is "enemy territory." Zone 1 is friendly, but may see enemy fighters over friendly territory. ie. a modifier in the gazetteer.) I will see if I can add this tho the rules.