Hello there 
Is it possible to make an edge, either by extruding a vertex or any kind of other action/tool… at a certain angle, like 45° 110,500°
Or if Someone could tell me how I can move a Circle (rotate/snap it whole to that corridor)
The corridor width is the same as the edge of that “circle”
Red-corridor
blue (example of an edge for snapping?)
one way would be to select your edge and extrude it normal
or use custom transform then extrude again to get a rectangle or square
and keep going on !
As the other person noted you need to use a custom Transform Orientation.
or use 3D cursor
set pivot point, then rotate by 360° / n / 2
n = number of angles in Circle
similar for any edge - extrude a straight edge (on any axis), set 3D cursor pivot, rotate as pleased
