The term "custodial interrogation" implies that the police are conducting an investigatory interview and that the subject who they are interviewing, is probably their suspect, and is not free to leave.
Custodial interrogation implies that an authority (police, corrections) conducts an interview with an subject which is of interest to their investigation with the condition that the subject is not...
Your question assumes facts not in evidence. If you are aware of officers using illegal drugs, it should be reported to the proper authorities, not bantered on a website.
It depends on the locality. Locally to me, the city officers carry a Sig 229M, county officers carry a Beretta 96D, and state troopers carry a S&W Sigma (I think...it may have changed). Each...
I doubt it. For one thing, while there is such a thing as "silencers", the best of them don't work very well, and the super effectiveness of silencers you see in movies or TV shows is pure Hollywood...