Outdated "manners" you'd like to see go away
So on number 1, I generally agree there but the purpose of it is that you’re more likely to put your weight on the table if your elbows are on there. Some, not all, tables get a bit tipsy.
On the rest of them, it’s a hard no. The internet may be a cesspool of incivility but I won’t let that creep into my real life interactions towards others.