'02 brake and suspension sensor Q's

[Chumley360]

Hello everyone. My wife surprised me with an '02 X5 3.0L last week and today was the first dry day I could go over it. I found that only the LF and RR wheels have brake wear sensors, is this correct? Sorry for my ignorance my only experience with wear sensors have been with them on all four corners. Second I noticed that there is what appear to be ride height sensors only on the RF and RR control arms. I don't have air ride suspension, so my guess is that these work with the hill descent control and/or the traction control. Is this a good guess? My AllData hasn't been super helpful with info on this vehicle. Thanks!