Answer: A British idiom, expression; I encountered it often in Yorkshire. "I could murder a beer right now." Means the speaker really desires a beer, would love to have one. "I could murder a cup of tea right now." etc.
Answer: No, you wont vomit bile. But if you have an obstructed gall bladder which stores your bile then you will vomit bile.You know the problem which is dangerous for alcoholics is liver cirrhosis and hepatic encephalopathy. Because ammonia will get into the brain.
Answer: The maximum allowed by law is .08 mg of alcohol per 100 ml of blood. This would vary somewhat depending on such factors as your size, if you had recently eaten, any medical condition etc. A normal adult could drink about one to two pints of normal strength beer.