Headlight removal involves removing the whole front bumper.
Remove push pins on top.
Remove bolts that hold on headlight/bumper
Remove bolts that hold on undercarriage shields
Remove 2 bolts that hold front quarter fenders to front bumper
Remove bolt that holds bumper to upper fender
Remove fog light connectors
Remove clearance light connectors
You can then remove the hidden bolt to the headlights to remove
That shouldn't be an issue. If there is uneven wear, there is a problem like stuck caliper piston or caliper binding. Unevenness could cause a squeak, but also can worn shims, too much lateral runout on rotors, thin pads, etc.
I have a 2002 IS300 with 32,000 miles. I not only have the sticky airbag, but the dash is getting funny too. I took it to the dealer I purchased the car from and asked them if they could get Lexus to pay for replacement of the whole dash and airbag. Haven't heard back from them yet. Looked on automotix.com and dash assy is $335 with free shipping. Airbag is more, found a new one on ebay for $375. It's an expensive proposition. Am looking into some sort of dash cover as a last resort.
I have found that electrical tape outside in the elements near wheels and such usually ends up sucking up all the moisture it can get and locking it inside the tape. It's better just to leave it out in the elements if you heat shrinked or an alternative would be liquid electrical tape that would seal it up without the seams.
Probably removing and reinstalling is what did it. Sometimes connections just get old and you have to unplug and plug to get them tight. A good example, some of my lights would not work like courtesy stuff. Well these were doors I never open cuz it's just me opening the driver door. I worked them a hundred times and they came back to life.
I believe it's dangerous to use any chemical cleaner on mass air flow sensors. There is usually a "heated" wire and/or circuit board in there and I believe the damage probably happened to the circuit board component(s). Even though it says safe, that may not mean it's safe for a direct hit from the stuff.