Bad to run a cold engine on idle whilst parked?

You should idle it a bit. Yes, running a cold engine is (mildly) damaging, but actually letting it work, such as when driving off, is more (mildly) damaging. With (mildly) damaging, I mean that there is a little bit more wear than usual.

I usually start it, then go out and spray the windows with de-icing spray (after brushing them, if there's snow), and when I've done that, it's warm enough to drive off. The gear box still feels like the oil is chewing gum, but it works.

By the way, I really recommend de-icing spray instead of scraping. Several reasons:

* You don't freeze your fingers from frost spraying off the scrape. It's a hands-off approach, just spray, then use wipers. If you start with the front window, it will be ready by the time you have gone around the car.
* The scrape is always blunt.
* The scrape can, if you are careless, damage the paint or trimmings around the windows.
* It gives a little protection against icing up as you drive away, at least for the first minute or so, which is the worst bit.
* It's faster.
* It's cheap. A bottle costs about $8 or so, and even a Swedish winter will only use up 3-4 bottles.