As stated above, the settings are in the display. They may have had to disconnect the battery which may have reset everything back to factory default. Check your owners manual.
Not sure what you mean by "when drive onto a bumper", but if you are saying you hear a clunk when you drive over a bump it seems it would be more suspension related than brake related.
Just the bulb, the fan attached to the bulb and a connector. I don't know what "driver" you are referring to but if it's part of the assembly it will be sealed already. It's not like a ton of water gets to the back of the headlights.
Hopefully someone will answer. I don't mess with this stuff, don't have it anyway. Good luck and welcome to the forum. Also, please state the year of your DJ and what system you have so others may assist you better.
I fully understand the logic and I'm sure it does remove lag, I've read about it on other makes and models forums I'm on that have vehicles using drive by wire. The science is sound. Just too much money for me. I can live with a little lag more than I want to spend $300 to do away with it.