You can't bike across the crosswalk, but you can get off your bike, step onto the sidewalk and walk your bike across the pedestrian crossing.

Forbidden how? Getting off your bike to cross the street?

In Copenhagen at least there are rules for when you can turn left on your bike:

http://www.aviewfromthecyclepath.com/2010/07/not-really-so-g...

I don't know how other European cities do it.