What year is her 540? Since my is a post 2000, I had to modify the brackets and the turn signals to have the umnitza headlight assembly fit. If she has a 97-00, it is a plug and play.
I don't have a low beam failure for my headlights because my car came with the factory xenon/Angel eye option. I do have the check fog lights warning because I have the HID fogs. I don't know about a fix for the fog light warning.
The HID conversion with parts and labor for the fogs, LED turn signals and headlights was about $1600. The parts from Umnitza were about $1050.
The low beam failure warning was addressed by someone on BMW-Forums I think.