They’re all lactic acid bacteria. The exact species might vary in different regions, like yeast, so kimchi from Korea and sauerkraut made in Germany might have slightly different species, but if you were to get local cabbage and make them both at home, they would have essentially the same bacteria.

The fishiness is from fish sauce and salted/fermented shrimp. You can make kimchi without those, just use something else for umami.

The bacteria are basically the same.

It could stop shrapnel from shells. Artillery was responsible for the majority of casualties in WWI, not guns.

So are you like a crazy person?