GRB's were discovered back in teh 1960's by accident. When the Vela Satellite program (designed to detect radiation anomolies from nuclear weapons detonations).
Also, despite being gamma emitters, GRB are notoriously bright in the visible spectrum. Typically they are found by looking for the other spectrums. longer-lived "afterglow" is usually ...
There are theories which suggest that the universe is like a giant spring, constantly expanding and collapsing. Its possible that pre-big-bang, there was another universe which collapsed, only to re-expand into the universe we know now.
But in reality we have no idea
This is a difficult question to answer. Physics really starts after the big bang. Scientist don't know about the laws, if any, before the first instance after the big bang. The time before and during the big bang is really the province of philosophy.