For quick manipulation I want to drag the “Wireframe without isolines” (only the edges) to edit the overall shape. How is the command called? Thank you!
Ok, I’m way out of Rhino, this would be a macro duplicate edges, select everything, then delete duplicates and you are left with only one edge instead of one.
Just turn off isocurves for the object (checkbox in properties) then ExtractWireframe.
Otherwise with the command _DupEdge you can window select the whole object.
OK, just re-read this - are you trying to directly edit the polysurface by manipulating its edges, or are you wanting to extract the wireframe as curves to do something else?
I’m making a short video soon about a pipeline. Trying to extract the edges, manipulate them like I would do with polygons and then work along these edges to create proper planes for the final design (no bend surfaces)
Isocurves are deselected this has no effect on the command.
SolidPtOn to manipulate a polysurface by dragging the corners.
Don’t quite understand what that means… if isocurves are set to off, ExtractWireframe will just duplicate all edges. With DupEdge, isocurves on or off doesn’t matter.
If you want to create a wireframe of the edges then DupEdges and select all the edges as @Helvetosaur suggested. If you select all the edges together then there should not be any duplicates. Then assuming the initial surfaces are all degree 1 planes the edges should be degree 1 curves/lines. Turn on the control points and you can move the vertices of the wireframe.
Be careful when moving the corners of any 4 sided surfaces. It is very easy for the 4 lines not to be co-planar which means the resulting surfaces will not be planes.
@davidcockey thank you! is there a way to make something similar as the ‘create solid’ command with history on to have the overall shape and get into every planar surface, extent or rotate all not breaking coplanar and then autoupdate the whole shape? thank you! H
you could give grasshopper a try. something like this is set up fast and you have all the freedom to move your parameters to test the end result in real time.
also SolidPtOn was mentioned by David, you can also use subselection with ctrl shift left click i believe using it on edges and faces to carefully change the finished solid.
@encephalon so finally the universe is forcing me to check out Grasshopper. Was always circumvent this the very smart way 
PS: do you know one course that is very good for the fundamentals? thank you so much to push me this route
Using Rhino commands only if you manipulate each surface individually, not by manipulating the polysurface. If you don’t have to keep the planes coplanar then just use SolidPtOn and move the solid corner points.
Move, Rotate, Rotate3D, Orient and Orient3Pt, Scale, Scale1D, Scale2D, ScalePlane, ScaleNU will keep planar surfaces as planar surfaces.
The tricky part is keeping all the planar surfaces as planar surfaces when moving something.
So @davidcockey this is apparently not so easy in Grasshopper, to keep all surfaces when manipulating coplanar? thank you!
i doubts that it is very difficult to move planar faces normal to themselves.
many/most of the commands of rhino are found in grasshopper. the basic concept is that you link the objects in rhino into grasshopper, meaning if you have a surface you place a surface component in grasshopper, right click the definition and select “set one surface”. you can call components quickly by double clicking into the grasshopper viewport and type its name e.g surface. those components can be linked with “sliders” and vector components to move in 3D space for example. you can also avoid creating base geometry in rhino all together by using grasshopper vectors (+sliders). its really not that difficult.
i learned it from school so i cant recommend any tutorials for now but there are plenty of pages under the grasshopper topics where people asked and got good start points. you can of course also read into the grasshopper primer but i would maybe avoid this as a starter and only read it when you further want to unfold its potential.
It is easy to move a single face in any direction. But what if the other faces need to stay connected and planar? The shape of the face which moved will probably have to change unless the polyhedron is a special case. Alternately the shapes and orientations of other faces, possibly all but one other face, could be changed. What is the design intent?
Geometry can be frustrating. It does not always work as desired. 
Hannes wrote that he wants to create a solid geometry on the basis of “create solid” which is already the key to keeping coplanar surfaces. moving and rotating those surfaces in any direction before creating a solid always results in a solid with coplanar surfaces.
of course messing with the faces afterwards is very constraint and can only be done keeping the normals unrotated. one way out is to use triangles instead of quads but then as you say what is the design intent.
Using CreateSolid is a way to Extend and Trim Surfaces automatically. But it does not provide direct control over the shape of any face.
sure not directly at least not directly visual, which then lead to bringing up grasshopper as an instant visual feedback.
other idea would be to use clipping planes grouped with surfaces set with SetObjectDisplayMode to wire and cut along to understand a shape and then intersect them.
The planar face may not intersect the clipping planes. And the question remains as what is the design intent? Move one face then extend/trim it and the adjacent faces until a closed polyhedron is formed? Or modify the adjacent faces so that they meet the moved face’s edges without modifying the moved face. Both are legitimate possibilities.