After watching Episode 1 of Season 3 I ask myself the following question, and it doesn't seem to make sense.

If Mycroft had his gunman pointing a gun on Moriarty's gunman, why did Sherlock have to jump? The gunman, who was watching Sherlock, did see, that he wasn't actually dead. Why didn't Mycroft "convince" the gunman before the jump?

If the whole district was closed off, why did Sherlock have to jump, since the only one not involved, who could see it happen, was Watson?
The whole outside world would only get fake anecdotes about the jump from the 25 homeless people, Molly or Watson.
He could just have involved Watson and then pretend to be dead without the jump hassle.
Why was it of any importance to fake it for Watson alone? The risk of him giving it away, is that all? I think Watson would be clever enough to be in on the plot.

Why not fake death only on paper to take out moriartys network?