Idea is closed. Solution was found (see coments).

To do good STL export with current implementation STL in 2.53 (eporter export object data), I need to:
*select object -> Apply modifier stack (because if i miss this step, next step will break my model if i have some deform modifier, like curve) -> Apply transformation (loc,rot,scale) -> export stl

if I have several objects:
*select objects -> Apply modifier stack -> Apply transformation -> join objects -> export stl

And if I miss some steps, model export wrong.


In blender 2.49 (eporter export object):
*select object -> export stl

And if I have several objects:
*select objects -> export stl

Less chance to make a mistake (I have a couple of times already mistaken in 2.53).


PS
Import STL 2.53 more good then 2.49