Point of sale. The devices you stick your card into to pay.

Chec out this article

Think you mean Trump in the second paragraph

Pretty sure they meant reverse dns :)

This Github is for detecting sound playing and sending it to Shazam. Perhaps you can use the features to capture audio and find another example of audio comparison for the other half?

http://galactanet.com/oneoff/theegg_mod

I also had issues trying to successfully set up vnc, specifically trying to connect from a Windows pc to the Linux box.

I would recommend trying rustdesk instead if it has the features you are looking for.

Https://rustdesk.com