Your window problem is 95% likely to be a broken plastic "jaw" on the regulator. You can get secondhand regulators really cheap (I had the same problem, about 2" from the top but JB welded the jaw). There are tutorials on the DIY links section of the forum on how to remove the w124 door panels (need a few minutes to dig up the links and paste in here). Before taking the steering wheel apart I would check for continuity with a multimeter at the actual horn noisemaker (in front of the radiator) which will show you which is at fault.

Edit: here you go -- PeachPartsWiki: Removing the Rear Door Panel
The front is generally the same procedure

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth