I was chastised by one of our German students for calling a professor 'doctor'. He said it was insulting. I thought he was full of it. The professor thing is a regional thing. Out here on the left coast, it appears that 'professor' is preferred. In the midwest, we called everyone 'doctor'. Apparently, from what I've learned (and from what Borek says) 'professor' is more appropriate in Europe (though I haven't taken a survey of all of the EU).
As for addressing the prof, I wouldn't address them by their first name unless told to otherwise specifically.