The first one is correct. Sometimes if there is extra information between em dashes like that, it can be hard to read smoothly in one go. (em dash is the name for the long hyphen –). You can try reading the sentence without the em dash to understand the core information: "... it is not because they are coldly clear-sighted and unimaginative ..." That makes the main point a little clearer. You can also try moving the middle section to the start: "... as those races frequently conclude, it is not because they are coldly clear-sighted and unimaginative ..." Hopefully that's a little clearer. This might not always work, but it can help when a sentence contains a lot of nested information.

When someone says they made something "from scratch", it means that they made it right from the beginning (and not just cooking either). So in your example, they didn't buy the buns from another place ... and maybe they didn't even buy the dough from somewhere else! They had all the separate ingredients and made the whole bun themselves.

Whenever there's any mention of being "blue in the face" in English, it refers literally to one's face turning blue when they are not able to breath. It's usually used to convey frustration or exasperation at something that isn't working, e.g. "I complained until I was blue in the face". Your example is using it as a poetic way of conveying the fact that those people are dead. It doesn't appear to have anything to do with the sea being blue. Hope this helps!

"Before" would be correct but "by" actually sounds more natural, so keep that. I would change the last part to "... the rest can be delayed ..." If you say "the rest can delay", it makes it sound like they are delaying themselves. "Can be delayed" is more accurate because it's delayed by someone else.