P: Panoramas - allow adjusting horizon and compression of field of view

You should upload an example image to show what you want

This isn't exactly what I meant. The horizon adjustment in panoramas also effects the projection of the whole image. It is kind of a perspective correction tool but with the panorama projection included. You cannot achieve this effect with the crop or transform tool in LR. You can find these tool in Panorama software like PTGUI or PanoramaStudio 3 Pro.

You can level the horizon in the crop tool or the transform tool.  

Thanks, that't indeed a good suggestion to fix that part of the enhancement idea.

You do have such a slider already, although not in the merge dialog. It's the Aspect Ratio slider in the Transform panel.