Having a parrot is an entire lifestyle, it's not just having a pet. There's so many things you have to do for/with them that isn't the same with a cat, dog, fish, ferret, etc.
Yes, Grey's do tend to be one-person birds. Some are fine in "flocks" (out in the wild, birds live in flocks, so living with people, their people become part of their flock), but others really do prefer one person. They are also very social creatures; the majority of companion birds want to know what you're doing at all times and usually want to be included. They also have complete minds of their own and, Grey's especially, are extremely intelligent. It's just like having a child between 2 & 3 and you're not going to be able to "control" what they do. You can encourage positive behaviors, but the best way to deal with unwanted behaviors in a parrot is to ignore it.
Again, birds are going to scream. It's in their nature. Sometimes it's a scream for attention, other times it's a scream simply because they are happy and when parrots are happy, they vocalize. Not all birds talk, even those of a species known to talk.
In regards to the sleep cage, for some birds it works, but I personally wouldn't recommend it. If you're going to keep her in the living room (which, I do think is a good idea; the highest or second highest trafficed room in the house is recommended), understand that she's going to scream. She's going to hear or see something on the television, or hear music or sounds that trigger it. If this is not something you can handle, then you should probably reconsider keeping a parrot. Again, they are not "pets", they are companions. Parrots also typically like to get as much sleep as there are dark hours; if you or your brother keep late nights in the living room, this would not work well unless she does take to sleeping in a smaller cage in another, quieter room. When my family only had two bedrooms, we kept our Goffins Cockatoo in the living room, covered her at night, turn off all the lights and from roughly 7:30-8pm would keep to our bedroom (we had a second TV up there, so it's not like we were going to bed that early) so as not to disturb her sleep. Even just covering her, but continuing to watch television in the same room is not going to work, because the noise will keep her up. She'll know someone's there.
I hope that helps.