Lots of bike boxes around here, although I think they're just painted on as part of a box ticking process rather than through any benevolence towards cyclists.
Many car drivers seem to think it's ok to stop in them - especially private hire drivers who I've noticed increasingly drive through the bike box, over the stop line and right up to the road studs. I've never seen any enforcement.
If someone is stopped in the bike box I always make a point of getting my bike in front of them anyway, where it's safe to do so.
Yep, me too if it's a car or van (I wouldn't risk it with a truck) - right in primary. Had a couple of comments, usually from big men through a window they've opened two inches. I just smile and point at the pic of a bike painted on the road...