You should be able to answer those yourself. Legal rights are not trumpt by illegal tactics, no matter what information is recovered.
No, but it happens all of the time.
Is any evidence gained through torture admissable?
If the police lie and say the person wasn’t tortured or do you believe that police don’t lie?
Are any law enforcement allowed to use torture to gain access to information?
Yes and police never lie and district attorneys never illegally withhold evidence from the defense....
You’re making a lot of assumptions that police, judges, and district attorneys play by the rules and that overworked public defenders have the time or the will to be great advocates for defenders.