Hey, for 5b:
Japan justified the invasion as China was falling into anarchy and they were simply stopping a threat to world peace
Japan was running out of resources. It couldn't feed its population that was growing by 1 million each year --> so they invaded China for their resources
5c:
Unanimous vote system was highly inefficient as everyone had to agree on something for it to be passed. Nothing ever got done because of this or it was very slow.
6b:
Chamberlain thought that Hitler would keep his word of not wanting to invade all of Czechoslovakia but soon after Hitler just decided to waltz right in and no-one did anything.
Appeasement, even though Britain wanted to avoid a war if they had confronted Germany in 1938, Germany would have lost. But by 1939, Germany built up its army and naval forces greatly, I can't remember the exact stats though.
6c:
Nazi-Soviet Pact threatened French border as they could send Russian troops as well as German troops there.
British-French guarantee was most significant as they didn't want to lose Poland due to its geo-strategic location against Germany.
When the Nazi-Soviet Pact was signed, or when Germany invaded Czechoslovakia, the others let it pass but only when Germany dared to step foot into Poland was war declared.
11b:
Marlene Dietrich and Fritz Lang became famous after creating what was labelled as the most technologically advanced film of the decade - Metropolis.
"Zeitoper" and "Zeittheater", styles of opera and theatre that was prevalent during this time period. Literally meaning opera and theatre "of the time"
11c:
Locarno treaties were also the pathway to Germany joining the League in 1926
Proportional representation was still an issue, though the coalitions were becoming more stable.
Spartacists were eliminated but there were still extremist right-wing groups around.
Various groups of society were still unhappy: e.g. Farmers' prices had been dropping since 1920.
That's just some stuff I remember writing, I'll add more if I remember anything else!