1) Well, if you have Google Chrome it comes with your browser. Grammar check is only for Microsoft Word. By spell-check, we mean just checking over your posts to make sure stuff are spelled correctly. People are a lot more likely to take you seriously if it looks like you made an effort to make your post readable.
2) [ spoiler=Insert title here ][ /spoiler ], but without the spaces.
3) Because we are a group of individuals that are forced to correlate with one another. In any situation where this happens, there will be fights.