Obviously they used to speak Latin, hence the name of their country, but what prompted the change to Spanish? My friend Oscar said he thinks it was because the people were having too hard a time doing math with Roman numerals. This kinda makes sense, because I can't even tell what year some movies and TV shows were made when they show the date with those letters. I can't even imagine trying to ADD letters or mutliply them and stuff.

Plus, Oscar is usually kinda full of crap, so I don't trust him on this.

Does one set of speakers look down on the other, or view one version of the language to be inferior? Also, is there much communication between the two (I've heard South American TV shows are becoming increasingly popular in Spain, is the converse true)? Would a native of Spain think less of a non-native Spanish speaker if they chose to learn the Latin American version of the language? And finally, are there any problems between understanding each other (or is it merely a different accent, like US/UK English)?

Sorry for all the questions!
Sorry, by "non-native Spanish speakers" I meant to say "non-Spanish speakers"