I'm sure Casey can have visitors, she just can't talk to them about what happened. But, I don't think there will be any visitors.
Casey can say whatever she wants to say, to whomever she chooses to speak to. Of course she can also say nothing, but whether or not she speaks is all voluntary - a matter of her own personal choice. There are no legal conditions imposed on her right to speak.
I'm sure her lawyer Baez would advise against it, but if Casey is out on bail for long enough, I wouldn't be surprised to see her granting interviews before the national media.