Short answers, pulled from the story.
Metal Gear was originally released on the MSX2 home computer in Japan on the 13th of July, 1987. An English version followed in Europe the same year. The MSX2 platform was never released in North America, which is why many Western players first encountered the game through the NES port.
Hideo Kojima directed Metal Gear after taking over the project from a senior associate at Konami. The MSX2 hardware could not support smooth shooting gameplay, so Kojima drew inspiration from the 1963 film The Great Escape and redesigned the game around avoiding enemies rather than fighting them, comparing the resulting chase sequences to Pac-Man.
The NES version was developed by a separate Konami division without Kojima's involvement or consent. Programmer Masahiro Ueno confirmed that the team was given a three-month deadline and ordered to make the port as different from the MSX2 version as possible. Hardware limitations also forced the removal of the Metal Gear mech itself, which was replaced by a Supercomputer.
The NES version of Metal Gear sold one million copies in the United States. It ranked second on U.S. sales charts in October 1988, just below Super Mario Bros. 2, and remained in the top ten through early 1989.
The portable radio transceiver allowed Snake to contact his commanding officer Big Boss and resistance members Schneider, Diane, and Jennifer throughout the mission. Kojima designed it to let the story advance in parallel with the player's actions, making the narrative feel active rather than separate from gameplay. It also delivered the game's central twist: Big Boss using the radio to lead Snake into traps.
The packaging illustration was drawn by freelance artist Akira Nishimura, who also created key artwork for Konami titles including Gradius and Castlevania. Snake's pose in the image was based on a publicity photograph of actor Michael Biehn as Kyle Reese from the 1984 film The Terminator. Kojima had no involvement in commissioning or producing the illustration.