There are no others you can acess other than the 1 in cheydinhal
The Dark Brotherhood Sanctuary is located near Falkreath.
The Dark Brotherhood Sanctuary is located in the Cheydinhal East Gate.
You have to go through the Dark Brotherhood questline. Innocence, my brother.
He's talking about the task he gave the player character in Oblivion, to kill all the members of the Cheydinhal Sanctuary. This quest was called 'The Purification'. When LaChance was a member of the Dark Brotherhood, 200 years previously, it had a code of honour that was usually strictly adhered to. He clearly does not approve of the ways of the current Dark Brotherhood.
Yes, you can.
Yes, the Dark Brotherhood is in Skyrim. You can get information on who to contact about joining them from the first town you arrive at.
In The Elder Scrolls V: Skyrim, Lun means "Leech".It is part two of the Marked for Death shout. This word of power can be found in the Dark Brotherhood Sanctuary, meaning it is only achievable if you take the optional Dark Brotherhood quests.You can find more about the Dragon Shouts and Words of Power on the official Elder Scrolls Wiki.
As far as I am aware you cannot which is a bit of a shame, but if you stop attacking one when they get low on health and move on to the next you can still do the same stuff.
It is given after Dark Brotherhood quest "Breaching Security"
You need to kill the old woman at the orphanage in Riften.
No, that's not necessary.
Sadly no, they say there are many but there is actually just the one.
There does not seem to be any mention of a person called Binyamin as a part of the Dark Brotherhood in Skyrim. There are mentions of people named Benjamin who write walk through websites for this game.