Thanks, BTW that was fast

Can't help with this.

Sorry, but I need to know (no wonder, I can do nothing without characters), so I'll try to ask being more specific
I downloaded everything from here:
http://download.gna.org/cal3d/sources/cal3d_miniviewers_binaries-0.10.0.zip
http://download.gna.org/cal3d/sources/cal3d_exporter_binaries-0.10.0.zip
You mean that I used correct version of Cal3D (since in Cal3D itself everything looked Ok, while in celtst it wasn't)?
Or CS uses a different version? Then where can I find suitable exporters (or something similar)? Or there are restriction on number of polygons per mesh (21K polys here)? It's just a mesh with one smoothing group, and in one piece.

You can do something like this:

Master world file:

<world>
  <library>path_to_file1</library>
  <library>path_to_file2</library>
  ...
</world>

Is it just plainly adds lines from these files to world file?
So if I want to have world mesh geometry to be stored in different file, what should I write instead of this:
=============================
<world>
    <textures>
        <?include textures.xml ?>
    </textures>
    <materials>
        <?include materials.xml ?>
    </materials>
    <plugins>
        <?include plugins.xml ?>
    </plugins>
<start>
<sector>room</sector>
<position x="1" y="100" z="100" />
</start>
    <sector name="room">
        <cullerp>crystalspace.culling.dynavis</cullerp>
        <meshobj name="floor">
            <plugin>thing</plugin>
            <params>
             <?include geometry.xml ?>
            </params>
            <zuse />
            <priority>object</priority>
        </meshobj>
            <light name="Light1">
              <center x="100" y="100" z="100" />
              <radius>250</radius>
              <color red="2" green="2" blue="2" />
              <dynamic />
            </light>
    </sector>
    <settings />
</world>
=============================
In other words: how to use these libraries, how to start/end these files (I know it sounds stupid... But I have to ask...)

Greetings!
I have a bunch of questions if you don't mind:

1.)
I tried to use 3ds max (version 5.1) model exported using "cal3d_exporter_binaries-0.10.0"
while I tried to view it with "cal3d_miniviewers_binaries-0.10.0" everything was Ok
But while I tried to use it in "celtst" I got this and I can't understand why... Is this version (0.10.0) is too old? Then where can I find a newer exporter?

2.)
I tried to use terraformer plugin (or whatelse) plugin for world creation, but got problems with high mountains: visible terrain geometry, and one used for collision detection (one you walk upon) are different and sometimes you're able to look under the suface. Is there anything I can do to avoid this while still having great level differences?

3.)
XML
By default we can only test levels with "world" file describing level properties, is there any way to split them into a smaller files using <?include xxx /> in any way? Because I tried this and didn't suceed (used <include> xxx </include> in splitted files)...

[only]

I don't think I understood everything correctly, but looks like you want to remove smoothing between faces. Is that so? Then I know solution in 3ds max for this, but not in blender. Anyway, it's not an additional geometry, it's just the way models looked like in the past (AFAIK, without vertex shaders).
So in short, depending on 3D modeling program you have to find a way to do so.
Here's an example: http://img78.photobucket.com/albums/v253/_Kriss_/char.jpg
Muscles are divided into different smoothing groups, so you see hard edges only where needed.
Did I answer your question, or I was incorrect?

Greetings!
Character modeling tutorial (not low-poly):
http://www.secondreality.ch/tutorials/modelling/body/body01.html
and check 3dtotal.com