Knights of Tezoth

1. A Knight is the face of the lord. Within the region, there is no one higher. However, in particularly important matters, subordinates may refuse to follow a knight's orders if they are not backed by a letter bearing the lord's seal. That is, if you, as a knight, tell officers to raise the banner and attack a neighboring region, they might refuse. The attitude depends on the region. Of those mentioned earlier—in Revnland and Tenerezza, they treat you with reverence; in Caboche, friendly; in Faregia, there's a special atmosphere.
2. Yes, it's possible.
3. Situational. It's better not to ruin the lord's image—it works both ways. On one hand, showing disrespect to a knight equals showing disrespect to the lord, but a brawl over some triviality can also be problematic. In short, you need to consider the lord's character and the customs of the region) But in any case, if it ends without injuries and isn't a systematic problem, it will likely end with something like "**why on earth did you do that, don't do it again, damn it".
4. If they come to complain later, they'll look at the situation. Generally, a knight is more trusted than some random person anyway, but this can be offset by systematic behavior, the presence of witnesses (if the truth is actually against them), and so on.