A house built in 1957 would not have knob-and-tube wiring, as knob and tube was phased out of residential use in the 1930's. Most likely it has BX armored cable. You should be able to see it where it enters the breaker panel/fuse box, or you can take off an outlet cover plate to see what kind of wiring it is.
Regarding polybutylene plumbing - it was used from 1978 - 1995, so a home built in 1957 shouldn't have it. Nevertheless, here's an article on how to tell if you do have it:
Polybutylene Plumbing - What is Polybutylene?
As for a missing breaker - if the knockout in the panel was open but nothing installed it's a safety issue, as it would be possible to stick your finger in there and be electrocuted.