Ammonia is an alkali and some people use it as a natural remedy for insect bites and stings. The alkali neutralizes the acid in the sting.
Yes - DO NOT SWALLOW AMMONIA.
they block pain receptors
No
They reduce pain.
For non-emergency treatment, where life is not at risk use ice to reduce swelling. You can also use a "skeeter stik", which are also often used to relieve pain and itching. If you don't have such a stick, use some diluted ammonia.
No, it should reduce joint pain
Keeping your finger in cold water will reduce pain.
Nitrogen-fixing bacteria do reduce the amount of nitrogen in the atmosphere by converting N2 into ammonia.
No
They reduce pain.
smoke weed
While kneeling chairs often encourage better posture, which can help back pain, it has yet to be proven that they reduce pain through their design.