> How do I model the Rope (B), because it will be stretched out if the cage gets deeper and deeper? Maybe solve this entirely via script, like in CR?

This is done like in CR via FacetTargetStretch=1 in the ActMap (of the rope object), so don't bother with that. Downside is, you can't have a texture but that's a feature of minor priority, I'd say.

> Is it possible to define some "Top Face" Parts like in CR? In this case the clonk should walk behind the Beam (C).

That's done in a not-so-nice way but currently the only way possible:
You have two models, one front part and one back part (cut in half by screen layer, z?). These two get assigned to two different objects, one back and one front (local Plane = higher than clonks;), the two objects are attached the mother object. An example is the current elevator case or the blimp.
This is far from perfect but - as I said - currently the only way to have a top face in a model.

> How the cage is handeled? Separate model? Same for the turning wheel, how it will be turned? Should I make some bones?

The cage is a seperate model, yes. Just like with the current elevator. And for the cage's top face, you'll need to split up the model again, sorry.
The wheel is turned via simple animation. Matthias should be able to help with that. You don't necessarily need bones (but you can use them if you think that's better / easier).

> Where do I comitt the model, when they're ready? It's really important that the model works in the first place – later the uv-mapping and textures will follow!

The resource repository or - in case you don't want to hassle with git - post it here with the request to someone to upload it into the repository. Self-uploading is encouraged, of course!

All in all I think this is a great model! It shouldn't get abandoned for the sake of the 'cliff hanger' model from above. It guess the two models can coexist. Maybe we can even figure something out to make the other one a little weaker (weight-lifting wise) for the advantage of cliff use. Also, this one is far more compact, that's an advantage in itself!