As you walk around Rivertown, you should hear someone mention that a boy called Aventus Aretino is trying to contact the Dark Brotherhood. This should add a misc quest to your quest list. Go visit him in Windhelm, and do the quest he gives you. Some time later, a courier will approach you with a note from the Dark Brotherhood, a threat of sorts. Find a place to sleep, and the Dark Brotherhood join quest will start.
Yes, you can.
There are 6 'main' Companion quests, and 13 variant 'Radiant' quests, some of which are one-offs or otherwise limited. Some radiant quests must be done before you can continue with the main quests.
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.
There are no others you can acess other than the 1 in cheydinhal
It is given after Dark Brotherhood quest "Breaching Security"
You have to go through the Dark Brotherhood questline. Innocence, my brother.
You need to kill the old woman at the orphanage in Riften.
No, that's not necessary.
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.
it never ends idiot
You can do any type of quests using any play style. it would be alot easier though if you were a stealth type character for the dark brotherhood.
Yes there are some but there are some in houses so be careful!