Hello. I will try to help you with this. Control arm bushings are a common item due to age. The bushing itself deteriorates and cracks which can effect handling of the vehicle and tire wear. Some places try to sell you the entire control arm at the same time so if they are only selling the bushings this sounds legit to me. If the veh. is still in the shop ask them to show you the worn bushings before replacement just to double check. As for the brakes it is not uncommon to need them at 35,000 but you are correct that you do have a sensor that will let you know when they are worn. Typically when the veh is in for service we check the brake thickness with a bmw special tool that will show 3mm if the brakes are at the "discard" level. This would mean that the brakes should be replaced at this time as the warning light will be on soon. Also, have them remove a wheel so you can take a look yourself. You should be able to judge by eye that your pads are worn and have them use the special tool in front of you. Nothing wrong with making sure you are not getting false information. As for the tires only a tread depth gauge can be used, or irregular tire wear on inner or outer tires. You do have a wear bar on the tires that when they are worn to the bar then you need tires. If you need any more help just let me know. Thank you!
__________________
Please hit the Accept Answer if you feel my answer was adequate. You can still reply to this post after an Accept.I would be glad to answer more questions or concerns you have. Thank you.
-BMW_Master Tech
