2000 E430 Brake Problem and Battery Question

[JBrouss105]

I have a 40k mile 2000 E430 that is starting to act up now that I have been using it to commute. The trifecta of abs/bas/esp lights have started to come on intermittently when stuck in traffic. For example, my morning commute is very stop and go and it usually comes on every day. My evening commute is less so and the lights never come on. I'm not sure how to proceed. Could this be a problem with brake pads? I haven't ever flushed the brakes, could that be an issue? I've heard that the brake switch is sometimes the culprit but since the problem only occurs on stop and go commutes I don't think that's it.

And finally, when should I replace the battery in the vehicle. It still starts fine but I've heard that an old battery can make the car's electronics act up. Any help/advice would be appreciated. Thanks