Leaving your door open is good dorm / neighborhood etiquette, because it's welcoming to visitors and doesn't stigmatize you as the village hermit.
Um....no.
Not in New England, anyhow. Fuck that shit.
What do you mean by "outer door"? Do you mean, for example, that there would be a "regular" or "inner" door (the main door), followed by a screen door or glass pane door (i.e. the "outer" door)? If so, I've never seen an "outer" door, like a screen or glass door, open inwards. I've never even heard of it.
Also, some people have vestibules/coatrooms/w/e in their homes, where there's a screen door, then the main door, which opens into a small room where you can leave shoes and coats and stuff, and then a door which opens up into the house proper.