Studying Latin is rough, but it's very valuable. It gives one a deeper understanding of the etymology and relationships of English words, it's a good foundation for following scientfic jargon, and more fundamentally, it's a great workout for the brain, forcing you to develop your memory, pattern recognition, attention to detail, and analytical skills, which can be useful in all sorts of ways. I think it's a shame that Latin is so rarely taught in high school anymore.
And what you say is true of just about any language -- the literal translation of the words is going to differ from the meaning of the whole, because language is often noncompositional, i.e. the meaning of a thing is not found in the sum of its parts but emerges from the whole. A foreigner might not be able to understand what "He hit the roof" meant when translated literally; the translation of the correct meaning (He became violently angry) may require a totally different selection of words.
