Is there any way / instrument to measure distances in cSurvey (in plan / profile / 3d)?
Yes for plan and profile: in design you can draw a 'quota' (h, v or free...). You find this objects in signs level.
There is no way to do it directly in 3D.
How can I change the type of profile? (extended / projected...).
You can't. cSurvey, now, manage only extended profile. In future I have plan to add also projected sections.