Western Slavic Languages

Most of us know that this includes Serbian, Croatian, Slovenian, and Bosnian. I know that S/C/B are very closely related, but the question is how related are they? Are they close enough that if I learned one would I understand the other ones rather well, or are they just mutually intelligible, and learning one would get me by in the other countries? If so, which one would be the best to learn. In an example, they say that Norwegian is the middle language, it shares vocabulary with Danish, but phonology with Swedish. How is it with West Slavic languages? I'd like to know, because learning one seems pretty attractive if it's 3 for 1.

>Would that conflict be the King Serb that ruled Yugoslavia, and the Croats killing upwards of a million Serbs?

By the 600 year old grudge I was thinking more of the Ottoman Empire expansion into Jugoslavia, but sure, the rest of those are probably still valid options.

>The places I go say that Serbian uses BOTH the Cyrillic and Latin alphabets. Is this really true, are they wasting that much of their time and energy to have 2 alphabets?

It's true mostly, although the Cyrillic Serbian uses is slightly different to the Russian, but not by much.  I wouldn't let that turn you off though, two alphabets are really the easiest part of it all and worthwhile learning so you can understand parts of other Slavic languages outside the reach of Former Jugoslav states.

Bonus prize, one of your first phrases:  Jebi se. (YEH-bee seh)  Serbian for go fuck yourself, reasonably certain it'd be understood everywhere.  Only use in extreme circumstances and never to someone larger than you.