I'm in ca where they do not typically terminate parental rights until they have an adoptive family in place. Their thinking is that the child will essentially be an orphan. So low risk here means they are just about to have parental rights terminated. If you are in another state then they may be totally free for adoption, I don't know how each one works. 

With phone calls they are more strictly structure and you can request a change if the time/day is challenging for the child. So normally it would be like the child calls mom every Monday at 5pm for 15 minutes....they arnt allowed to just call whenever and if they call at an unscheduled time you don't have to answer. But like I said, all this stops once rights are terminated so if you are only wanting legally free you wouldn't necessarily have to deal with that (or if your state doesn't free them until the adoptive family is decided you may get a child a few months before tpr and have to deal with the visits and phone calls for a few months until court).

And you are correct, you have to foster the child for 6 months before the adoption to make sure it's a good fit for everyone. 

I have only had little kiddos so I havnt experienced it first hand but yes bio parents making big promises can be very difficult for the child. If you have a good case worker  and you tell them what's going on and how it's affecting the child hopefully they will law down the law with the parents and report it to the judge if it continues. Sometimes the judge will reduce phone calls if the parents ignore directions. A lot of how the case goes depends on the judge and case workers unfortunately