Federated means that any instance that is federated with them receives their content and can bee seen on that instance.

Defederated means they are not federated anymore, thus blocking both users and content.

It’s usually done to combat content you don’t want on your instance

Don’t have the Fold but the Flip 3. I’d say it is pretty much as resistant as any other phone I had. If not more so because the main screen in protected when folded

Definitely is. I forgot the actual name of the writing style, but for children’s books it is also not uncommon to have kanji with their hiragana transliteration above/beside it. Requiring someone to immediately write kanji when they learn japanese, especially as a secondary+ language is insane