s8 1998 vfl questions about questions :D

So, for a second,
1. maximum air mass, i.e. 4 gear fully turned out, 260 g/s, does that fit?
2. I have the problem that the Esp / Abs sometimes completely fails. In the error memory, speed sensor is located at the front left short circuit after Plus. But if I drive like this I don't notice anything. So all this is just sporadic. Is that still the sensor or should I control something else?
3. ESP sometimes regulates too soon. I noticed at the reading blocks going through that there is always brake pressure, something under 1 bar. That's not a lot, but does that have anything to do with it? Oh, that's normal?
4. CD changer (orginal , bosse, no navigator, I think chorus is called the part) only shows Err 3, no matter what I do and do... Error memory empty, what's with it? The rest of the radio goes perfectly...
5. Brake lining wear indicator lights up, but surface is still more than sufficient (estimated to be 80 % still) I then measured and noticed that the right surface no longer has a passage. Since I didn't find where it was broken, I just connected both ends directly behind the plug, I now also passed through the plug, only as soon as I start driving goes directly on the wear indicator. Where can I control things in a meaningful way now, suppose a cable break somewhere, or should I check something else?