Short answers, pulled from the story.
A computer keyboard is a built-in or peripheral input device modeled after the typewriter keyboard, using an arrangement of keys that act as mechanical levers or electronic switches. Each key press sends a scan code that tells the computer only which physical key was pressed or released, leaving the interpretation to software.
Teleprinter-style keyboards have been the main input method for computers since the 1970s. The computer mouse supplemented the keyboard from the 1980s, and the touchscreen joined in the 2000s.
ISO, ANSI, and JIS are the three mechanical layouts used by most full-size keyboards, named for the bodies behind worldwide, United States, and Japanese standards. ANSI keyboards place the Enter key in a single row, while ISO keyboards give it an inverse L shape spanning two rows.
Full-size keyboards are described by their total keys, such as 101, 104, or 105. Keyboards matching US conventions typically have 104 keys, while the 105 key layout is the norm in the rest of the world.
A chorded keyboard associates actions with combinations of key presses rather than one action per key, letting it produce more actions from fewer keys. Douglas Engelbart invented the first one-handed keyboard, which was a chorded keyboard, and court reporters use chorded stenotype machines to type a syllable per stroke.
Yes. Unencrypted wireless Bluetooth keyboards can be sniffed by a covert listening device in the same room, and keystroke logging captures typed keys through hardware or software. Keyboards also emit electromagnetic signatures, and Neal O'Farrell described how former spooks captured a user's ATM PIN from a van parked across the street by decoding keystroke signals.
The first electronic keyboards of the early 1970s used individual switches costing 80 to 120 USD, with popular reed switches sealed in glass capsules. Key Tronic introduced capacitive switches in 1978 and reached 60 dollar prices, and later advances such as monoblock housings and membrane sheets drove the cost well under 10 dollars.