I need some help with the look of the outside of the chamber.
I know that the chamber can stand on rails, have those panel moving handles and big aperture signatures on walls. Are there any other elements on the outside of the chamber? And what texture does it use?

Arm_exterior models are often used outside chambers, there's a bunch of nice models for that. The plasticwall002a and plasticwall003a texture (yellow/black with crossing beams) is used for the outside of chambers a lot. Search "BTS", "factory", "backstage" and "concrete" to find some of the other textures.
Here's a tutorial by Arachnaphob on BTS scenery:
https://m.youtube.com/watch?v=imAtUnSLXnw

Thanks, that helped