Apologies if these questions have already been answered, but there are a few things I didn't understand in this episode:
1 - Why did Moriarty kill himself? Yes, because he didn't want Sherlock to 'win', but what exactly did Sherlock do to convince Moriarty that Sherlock had 'won'?
2 - Was there any relevancy, in terms of Moriarty's plot, to the assassins assassinating one another to get to Sherlock? And why did Moriarty want the assassins to think Sherlock had the 'key'. Why did he pretend to give Sherlock the key?
3 - Why did Sherlock tell John, just before he jumped, that he was a fraud? The assassins were instructed to lower their weapons when Sherlock jumped, they weren't instructed to do anything with regards to Sherlock falsely confessing he was a fraud. So why did he make the false confession?

Sorry if I'm being terribly dense here. It's a fantastic episode but I didn't understand it all. Thanks for any replies.