I doubt you can get the motor out without removing the regulator - it's just too tight through the access port in the door panel. OTOH, removing the regulator/motor assembly involves removing 4 10mm nuts and unsnapping the wires in the plug to permit extrication. The two vertically spaced bolts retain the window channel, with the top one doubling up to hold the regulator assmbly. The two horizontally spaced nuts retain the assembly. Not that hard. You will have to wiggle the window up and down to permit you to remove the nylon slider from the alloy channel at its base. If you are frozen up, break the plastic slider and follow my web pix to replace it. It's a $2 part.
As for the # of teeth, I don't know. I'll take a look in my W126 book to see if I can crack it from the pics, but these tend to be of poor quality. I'll let you know.