While the Palace is close and easy to get to I would shoot for Oase and World, I know of several big busty blonds at Oase and a few at World. While Palace has them they tend to be operators (from my experience) someone else might be able to recommend someone.

The European look is more natural boobs rather then bolt ones but it is catching on and becoming common. You'll find more girl next door but you will also find the slutty porn stars as well. I'm always amazed when I meet one of these gals on the street or before she comes to work in her normal clothes. Then see her in the club with her make up and 9 inch heels strutting her stuff. Funny what a women thinks is sexy.

Really depends where you go for sex outside the room. Schieferhof "Bernd's" its fairly common. But at World, Oase and Palace you'll be hard up to find it but it has happened. You might see it in the Kino's (porn theatre inside the club). Blow jobs are most common in the club in front of guests or in the kino. Again at Bernd's it very common and expected. But I don't think they have as many young, porn star gals but they do have a few busty blonds. My last visit the place was loaded with must do women but NO guests. Things change....

Prices don't change if you have sex outside the room (Zimmer), remember the word Schlüssel (key) as some clubs the girl will ask if they should get a key in German.

In all fairness the talk about everyone having sex all over the place, well swinger clubs is where you most likely will find this to be normal. Most big clubs it can be found but not that common. When rooms become scarce women start blowing guys anywhere they can to keep them entertained and if you find a gal who does not care YES she will do you on the bar, if they let her.

Your selection of clubs appear to be very far apart, Palace is in Frankfurt, Armetis is up by Berlin and Globe if it is the one I know near Dusseldorf all 100's of KM apart.

You might try looking into organized tours and google fkktour