Idling - Toyota Corolla, 1.5L, 1997

Generally not enough.
This, of course, saves fuel, but the engine is not lubricated enough, and therefore more wear ...

You remove the load from the engine, so it stops vibrating due to the fact that it is easier for it to spin!

There is vibration ... but not always ... when there is I switch to neutral. Vibration disappears ...

I, too, on D when you stand on the brake about the same picture! Do you feel the vibration from the engine at such speeds?

yes it is for everyone!
on d and on the brake, + - 100-50 rpm

I honestly did not notice the stickers on the hood and under it with the RPM inscription) you need to look again ... or find the engine manual)

Is there a sticker on the hood? I have 580-700 rpm written there, though 4a-fe engine