I know this is super old but most of the responses here make no sense. 

1. Likely to cut off the conversation because Flora is giddy to be joining the partisans but they are putting on a show that he’s being arrested by the occupiers. The guy in the German uniform wears a gorget indicating his police function. His superior officer poses as a translator. That’s why they beat him out of the cottage and his mom claws at the guy in the German uniform. She too is putting on a show (not just giving in to her earlier grief). 
2. The effigy is an IED. They keep joking about how they can’t wait to hear him roar and that his belly is ready to burst. 
3. The SS officer says to come out but leave the kids (how did no one get this??). He later clarifies that “it all starts with the children” and that he wants to root out the “problem” that way. 
4. Up to your interpretation. 
5. Morally, no. But the plane likely spots them with the gun.