What seems to be the quest of all these characters with telepathic powers of the Runciter team? Are they heroes who want to save the world?

I guess this depends on what your deffinition of hero is. Joe's savior is Pat Conley. She offers to help him get out of debt if he passes her to work as an anti-telepath. However, Joe is loyal to Mr. Runciter and passes her simply because her powers are great. At the bottom of the test, he indicates she is dangerous.

Joe demonstrates his loyalty towards Runciter when the bomb explodes on Luna. Despite the fact, his boss is dead, Joe puts Runiciter's on half-life before anyone else and rushes to preserve his body. In Zurich Joe becomes hysterical about Runciter's death and his friend Al has to calm him down. In the end, he suggests Joe has a relaxing evening in a hotel room with Wendy Wright. Joe is deeply in love with Wendy and agrees with the suggestion. Unfortunately, the next morning, he finds her dead. It is interesting at this point he shows little emotion. This does not prove Joe is cold hearted, but demonstrates how much he works on his instincts. He knows something is very wrong and that he must focus on the job at hand. He takes Wendy's body back to New York and with Al goes about trying to work out what is happening.

Joe's instincts work well when the world around him is regressing. Joe has to get to Des Moines, but all modern modes of transport are unavailable. Instead, Joe manages to work out how to use a LaSalle car and then drives it to an airfield. From here he manages to pay a pilot to take him to Des Moines, a feat perhaps none of the others could have achieved. Nevertheless, Joe's natural instincts can also work against him. For example, Joe's recommendation of Pat Conley may have lead to Runciter's death. For his instincts to work well, Joe needs a stable presence with him. Initially he finds this in Al and then later with Runciter himself. Both of them help him to focus his energy towards the reality, or in this case, the lack of reality, of the situation.