The use of incense to remember ancestors was spread widely across Asia by Confucianism. Chopsticks look quite similar to incense sticks, so it makes common sense to have this tradition.

> 1. I have seen Japanese people do approximately half of the things on the list.

There are people in Japan who are rude or who do not have as good manners or etiquette when they are eating alone!

If everyone followed all manners all the times they wouldn't really be encoded woould they?

Both of the serious ones are not specific to Japan, I got told off in China for standing chopsticks up in rice. I suspect anywhere with a significant Buddhist population will have the same taboo.