Jeez, ok here it goes
1.- TJ remembers, but decides to keep quiet to "prevent more troubles". Remember that he is just against any sort of violence. That and the fact that Sydney was basically killing him and Chase saved him.
2.- Yeah Socket man is Flynn, there is not really a purpose of his own, although he do regains control every now and then. But the "evil of echo" is mainly in control. (There are theories that this evil might be "the other" mentioned in Adastra series.)
3.- And no, I don't think he is there to prevent someone to be unjustly killed, he did not prevented Carl's predecessor to kill his lover, and in Leo's route he does not prevent Chase's death. He exists to protect Echo secrets, the evil and curse of Echo exists because of them, and as long as those exists, the evil can feed.
At least that is my understanding of things. If I misunderstood something please correct me.