This is an excellent post. Thank you very much Elvis for doing this.
I actually had to refer to this post twice. I still have my 2003 530i. I replaced the FSU once with an oem part I purchased online at one of those companies that sells BMW oem parts. It lasted less than 3 years.
So this time I decided to get one from a BMW dealership online that discounts parts.
I have not read every reply but I wanted to say I found the easiest way to remove the wire harness and the FSU was to lay on my back with my legs toward the rear of the car and with my upper torso and shoulders resting underneath the glove box. Doing so I was able to get both hands in there to do the job.