Maybe I am not naming the style correctly, but the examples should give an idea of what I mean. Can somebody explain what technique and attributes I need to create photos in the mentioned style?
This answer is sort of weird.
You need to learn to 'see' like the photographers of that era did. Understand their processes, understand the limitations of those processes, and the steps they took to get around them.
The emulsions of the day were slow. Exposures were measured in seconds. Side lighting was often used to pick out the subject from the background. Sepia was used as a method to get better fixation.
Depending on the era the emulsion may have had obvious grain, or reduced contrast.
One exercise that may help is to look at MANY images (your local historical society or government archives may have originals that you can look at.) Look at many images and catalog them. What makes them 'silver age poetry' style. I would suggest that you look at more than portraits.
I think you will find that you need two things to create good art in this style.
Appropriate lighting. While a diffuse side light is critical in the first two examples, the first image clearly has a second light source highlighting the ear in picture left, and the knap on his suit on his shoulders.
Post processing. You will probably want to add grain, blur, and play with contrast and brightness.
I'm curious that you see these images as being of similar style. I see them as quite different, and strongly prefer the first one of the three. The 2nd one is just a snapshot, with flat lighting that says little about the person's character. The third one lacks detail, and has such high contrast that it looks like a pen/ink/water wash drawing as much as a photograph.
Anyway, good luck.
If I understand you correctly, all you need it the correct light. For example in this case, a very diffused window light was used (overcast day, dirty window on the right): http://www.flickr.com/photos/normis/3983619211/in/photostream
An added bonus would be a self developed black and white film, and a camera with nice glass (they even have a term for Leica glass - "Leica glow").