Here, the author is full of thoughts, mainly because of the war, people like duckweed, the future is bleak, and I have been away from home for many days, but I don't know if tomorrow will be safe. They think that their family is like this and the world is like this, so they are "full of meaning".
It means mood.
Ten thousand weights means a lot.
Stress, like "worm", has many meanings and overlaps.