Most intros are just a surprise omg where am I sort of thing. Uhm Sam is one of those people that might do some research before contacting the network (if you wanted to go that way) so you could have him intro to the network knowing a little about the place and even knowing Dean is there if you want because Deano's been here for geez two years come February so he could post with that knowledge looking for him. It's kind of whatever you want to do.

Oh God, yeah absolutely. I need to get with mary mun and 100% verify it but I think he's living in a garage apartment above Mary's garage and Mary has more rooms proper in the house so really, Sam's got his pick of either living in the garage apartment with Dean (he'll totally stalk/watch Sam sleep/check up on him anyway for weeks) or in the "main" house with Mary. Sammy won't be left to fend for himself.