Magic The Gathering: Grand Prix Providence?

So I am going to Grand Prix Providence which is a big legacy mtg tournament. I have never been to a grand prix before and I am excited. I was wondering what specific tournament rules do they make you abide by when playing. What happens when you accidently drop a card from your hand or see a card from your deck? Also what are some popular legacy decks right now, and is Ravager Affinity a decent deck for the metagame? What are other things that are frowned upon or against the rules when playing in a large scale tournament like this?