3 questions- easy for those who know

1.Ben tell Luke in ROTJ that Darth Vader was kept from knowing about the twins by both he jedis and the Emperor, but in ESB, Darth tells Luke. How come? How did he know? Why did he not act on it before?

2.Where is Mace Windu, and Qui Gonn Gin in the scene in ROTJ where they all stand around chatting about how cool it is being a ghost? Gone for more pies for Anakin?

3. Darth Sidious, Senator Palpatine, - how does he become the Emperor? Why not stay Darth Sidous?

'Hey wait, this kid has the name Skywalker, and he's right about the same age from when I was nailing that Padme chick 20 years ago, hmmm.... could he be my....? naaaaaahhhhh!!!'

Playing basketball.

Because getting rid of the Jedi required whipping up Anti-Jedi sentiment in the Galaxy, and no one really knew the Emperor was a sith.

The Force, he could sense it.

Dunno, wasn't close enough to sense him perhaps? He couldn't sense him and the rebels on Hoth until the probe droid found something. Also, he couldn't sense any more than 'the force was strong with this one' in ANH in the Death Star run so it took him a while to figure it out/sense it. Luke took a while to figure out that there was a connection with him and Leia (Cloud City rescue of Luke).

Luke probably doesn't even know who Mace and Qui Gonn are, the three he did see were close or related to Luke. Plus, we don't even know for sure (although probably will die in Ep3) that Mace Windu is dead yet in ROTJ.

Wait for Episode 3 for an answer to this.

You need to wait for the re-re-release of ROTJ when Lucas bluescreen paste them onto the film.

I'm pretty certain about this