Accents: á, é, í, ó, ú. Yes, they do assist in the pronunciation. They are natural part of the word in question and should not be omitted (if you ask any Spanish language teacher). In some cases, words with omitted accents may have completely different meaning - but, since in real life words form parts of a context, it is not hard to see that a writer forgot to put an accent. Which is common for quick typing like sms or messengers, especially for younger generations. Not only (missed) accents, teenagers would frequently type abbreviations that I think a google translator would not understand (but another Spanish speaking person will). A separate letter: ñ. It should not be considered as "n"+"~". It is a separate letter with a separate key on a spanish keyboard, and is pronounced differently.