1) Using the mouse-wheel to zoom is much more sensitive when I have a reference selected than when I have nothing selected.

2) Using shift to rotate the camera works properly when I have a reference selected, but when I have nothing selected, the vertical axis is inverted when moving the mouse (I look down when I move the mouse up). The horizontal axis is fine, so I can't simply set a negative value for rotate speed (this would make the vertical axis work fine, and the horizontal axis inverted)

Can I fix these? It would make navigation much, much easier.

Another issue: The "Movement Speed" property (the speed at which you can move selected references around the world) also has very different effects depending on whether you're in projection or orthographic view. The movement speed is about twice as slow in orthographic view. I've been searching online for fixes to these problems for hours, but I can't find anything.

I really need to be able to look / move around 3D space comfortably before I bother trying anything else, and these basic interface problems are driving me crazy.

All I can say is "you get used to it".

For fine-grained zoom in/out, I generally hold down the V-key and move the mouse forward/backward. Of course, that doesn't work if you're editing navmesh...

And I never look around without at least something selected.

Since I don't wanna open a new thread for my probably dumb question I'll ask it here:

I'm completely new to the GECK and am trying out the tutorial right now. Now I wanna drag an object into the render window, but it somehow doesn't work. So I click on the object in the object window, hold the left mouse button and drag it into the object window, but it doesn't appear there. What am I doing wrong?

Odds are that you're probably trying to put it inside another object. Specifically, if the camera view point is outside (or inside) an object's boundaries and the drop point is on the other side of the border, it won't work. You'll see this happen a lot with invisible entities like fog/lights, but also with larger models like the houses in Primm.

Move your camera view, try dropping at a slightly different location. Zooming in really close to the surface where you want to put the item works, or putting the item down elsewhere then moving it into place (either by dragging or by editing the XYZ coordinates).

Well, it is the first object I wanna place in the render window, so it cannot be inside another object.

I also tried putting it in different locations and zooming in/out, but I'm still not able to palce it.

Just forget it, I didn't double click on the copied cell in the cell view window. :facepalm: