increasing amount of side faces on object made from cylinder Is there a way to increase the amount of side faces on a cylinder-like object  after manipulating the object in edit mode other than using subsurf and creasing every single edge? The edges selected on the picture are the ones I'm refering to.

I modeled a now somewhat complex object starting with a simple cylinder, assuming that the amount of faces on the side would be sufficient though there's a need to increase it now.

Also, does the shading method (smooth/flat) affect the model in any way when exporting to other file formats?
Mesh Objects in Blender don't have an Edit History that would allow you to edit a parameter somewhere at the start of the Object's life and have that propagate through all other operations to the present. You can't in your example change the tube's vertex count after you've made edits to it.

But it is possible to reconstruct the object quickly with the desired vertex counts. For instance use the Screw Modifier to Lathe the profile around an axis. The Object's center can be used as the rotation coordinate or an Empty.