The Mechanics of a remote control - light 
No light, nothing.
Customers see an LED and think that it should flash bright red when they press a button, but see nothing. Some animals are purportedly able to see infra-red light. Some are thought to see trails left by rodents i n the infra-red light end of the spectrum. We humans are not known to see infra-red light.
Some remotes have the LED set back and hidden behind a glass screen, others have it sticking out the end a little bit. Maybe there are advantages to both setups. It is a little easier to make without the glass sc reen.
A fairly well know method of "seeing" it flash is to point at a CCTV camera / mobile phone. A bluish white fast flicker can be seen on the phone screen/ CCTV monitor. However, many phones have an infra-red filter so always test with a remote control that you know is working first.
The LED is driven at max power. Overdriven really. As it is not held on continuously it can cope with the high power supplied to it.
Most remote controls will have a range of about 8 metres and will bounce off mirrors. Extending this is quite a challenge. It is hard to obtain higher power infra-red LEDs. There are plenty of visible light LEDs that have much greater power output, but not much in the way of IR ones. We did build a board with over a hundred standard LEDs and the range doubled. I suspect the use of lenses to focus the beam would be needed to ge t a very long range.
Frequency tolerance
Most devices, TVs / DVDS / Hi-fi systems will accept a degree of latitude when it comes to the frequency of the remote control transmission. Some, however will only work if the frequency is very precise.
If the clock running the chip drifts away from the desired frequency both the output frequency changes as well as the lengths of the bursts.
Some devices will work with as much as 10% off from the specified frequency, others will halt functioning at 1%. The battery level, temperature and crystal state will alter the clock speed to some degree. Externa l crystals appear to be far more accurate than those built inside the chip itself.