Muggles' Guide to Harry Potter/Magic/Floo Network

Overview
The Floo Network is the network of fireplaces able to be reached by Floo Powder.

Extended Description
When we first see people traveling by Floo Powder, no mention is made of the Network as a separate entity; you simply travel until you reach the correct fireplace. In Harry Potter and the Goblet of Fire, where the Network is first mentioned by name, we are told that the fireplace at Number 4, Privet Drive has been temporarily added to the Floo Network. And in Harry Potter and the Order of the Phoenix it is mentioned that the Floo network is being monitored. This possibility that it could be monitored rules out its use for getting Harry out of Privet Drive and into a safe house in Harry Potter and the Deathly Hallows.

Analysis
The Floo Network can be used for travel or for communications – you can allow just your head to travel, and leave your body where it is. This ability to communicate by allowing just your head to travel is used by Sirius Black on several occasions, by Harry on two occasions, and by Amos Diggory on one occasion.

There is apparently a sub-office of the Ministry of Magic, called the Floo Regulation Panel in Harry Potter and the Goblet of Fire, which is responsible for keeping the Floo Network operating.

In Harry Potter and the Half-Blood Prince we are told that the Floo network has been connected to Hogwarts to allow students to return to school after Christmas. This seems a little odd, as we already know that the fires in Gryffindor tower, the Defence Against the Dark Arts and Potions masters' offices, and the headmasters' study are connected to the network; presumably this means that the fires in the Head of House offices have been set to respond to people desiring to travel to Hogwarts. Perhaps it is possible to make a "concealed" entry in the Floo network; you need to know the name of a fireplace before you can get there, perhaps it is possible to have some fireplaces be "ex directory" so that you need to be told the name, which presumably would not be obvious, before going to that grate. In this case, "connecting to the Floo network" would actually mean "publishing a new name for the head of house's fireplace".

Alternately, while Dumbledore appeared in the fireplace in his own office in Harry Potter and the Order of the Phoenix, in almost every other case we only saw the use of the Floo network into Hogwarts for communication. It is possible that there is some mechanism that prevents anything larger than a head from traveling to any other fireplace in Hogwarts. Such a security mechanism would certainly be a reasonable precaution for a school. In this case, "connecting to the Floo network" would involve removing the size limitation so that a whole person could travel to that fireplace.

Questions

 * 1) Number 12, Grimmauld Place is on the Floo network – Harry is able to use the Floo network to talk to people there. As its existence is only known to members of the Order of the Phoenix, how is it possible for the Floo Regulation Panel to keep it connected? Is it even necessary for them to act to keep it connected?
 * 2) Would Floo network connection be a paid service, like phones? You have to buy Floo powder, do you think you'd also have to buy connection to the Floo network?