In "One of Us", the Flame had new, shiny color TV monitors and a modern-looking console. In "Enter 77", the Flame did not have such a console, but had numerous wires hanging from the ceiling that appear to have been cut off and ripped out. After the discharge, the Others ripped out the monitor console and transported it elsewhere.
On the blast door mapthe Flame is numbered #4, the Station Orientation Videos show that the Swan was #3 and the Pearl was #5. It therefore seems that the Flame was once involved in DHARMA scientific experiments, quite possibly in Information Technologies and Artificial Intelligence, rather than just being a communications hub and comms station for the Island.
The reason the dish communications part of the Flame wasn't located in the Barracks is because the sonic barrier rendered the incoming and outgoing signals useless - the station had to be outside of the contained area in order to function.
The dish uses Electromagnetic Radiation, while the fence uses sonic vibrations, like sound. The 2 would not interact directly.
The station is a location of the DHARMATel servers/exchange.
The explosives and self-destruct were installed after conflict erupted between the Others and DHARMA - not when the station was built.
It is the intelligence station, since the DHARMA days, an evidence is the quantity of documents achieved on this station (Protocols, procedures...)
Originally, 77 was a request for backup from Onshore DHARMA personnel, however, Mikhail reprogrammed the computer with a Chess game and made the code explode the station after a few minutes.
The food drops were initiated from the Flame, and it seems reasonable to think that someone, probably from DHARMA, was there at the station when the drop occurred in "Lockdown".
They are time-based. However, when Locke wins the chess game, the computer video indicates he has accessed a "manual override". This could indicate that much of the operations controlled by the Flame are/were automated and thus the drop in "Lockdown" was a regularly scheduled event.
Heavy water is not a power source in itself, but can be used as a fuel source in a fusion reactor. Scientists have been able to achieve a fusion reaction, but thus far the energy put in to start the reaction has always exceeded the energy produced by the reaction, making fusion an impractical source of energy as of yet.
It makes the most sense to me that (being called the Flame) it was literally a signal fire, truly a communications hub. In the basement there were all the DHARMA manuals etc, and the station was rigged with C4 so that if the hostiles did attack, they wouldn't be able to use and abuse DHARMA equipment to contact the outside world. Something like that.