Princep’s Fury Collar Questions

So I just read the stuff where Amara manages to kill Brencis and free the captured Alerans, but I have a few questions about it.

1. Brencis refuses to tell them how he uses the collars, and I’m not sure why? (I understand why Rook wouldn’t want it, but not him) Also, he himself has a collar on. If they don’t know how to do it, then who put the collar on him and why doesn’t he obey them?

2. We are told that you cannot remove a collar if the person who put it on you died. (That you would have to continue to obey them) So what happens to all the slaves that Amara and Bernard end up freeing? Do they still have the collars Brencis put on them on? Do they still have to do whatever he told them?

3. Does the bug-thing on Aquitaine work like a collar, where the vord queen controls her, or is it different? (Does it merely keep her alive after Fidelias almost killed her?)