New to the FR - a few issues...

I don't think the rear view mirror is unusually big, I have no problem with it and I think it's the same size in all versions of the mk2 Leon. Unless you're really tall, I can't see how it's blocking your view of anything on the road in front of you, I have to look slightly upwards to look at the mirror?

The display should go off about 30 seconds after you remove the key.

The mirror is comically big, took me a while to get used to it and I'm still forever head butting the thing if I'm getting something from the glove box or passenger floor well. It's a lot further in than any other car I've had as well.