How did Duke get an alligator tail on him if he was drunk and on drugs the whole time?
Same as for the half of a plastic bull with high heels in/on the toilet; it's Vegas, they have unlimited credit, so everything is a phone call away.
Why does Dr. Gonzo always say "As your attorney, I advise you to..." before suggesting something incredibly foolish, risky or dangerous? To keep Duke out of trouble of course, by putting the responsibility all on Gonzo who can legal-bullshit his way into and out of anything.
As his actual attorney he pretty much has legal say for any of Duke's actions. It's pretty much him letting Duke off the leash when he asks for advice on certain matters. He also knows the legal loopholes so he may know how to get them both out of trouble.
Which is remarkably true to life. Oscar Acosta's legal career was marked by a mixture of political activism and Refuge in Audacity — he supposedly set a judge's lawn on fire with kerosene the night before facing him in court, and remained confident that no one would ever believe it was him.
I realize I'm an idiot, but something about this bugs me. With a bit of luck, his life was ruined forever. Always thinking that just behind some narrow door in all of his favorite bars, men in red woolen shirts are getting incredible kicks from things he’ll never know. Why would his life be ruined and why does Duke consider it fortunate?
My guess is he means "ruined" in the same sense that people think drug users lives are ruined. Basically Duke is saying that the guy will probably start feeling like trying drugs in the future.