Yes, it's possible to find negative rates with operators who use dynamic pricing. Buy cheaply during panic dumps and sell cheaply during FOMO rallies.

Yes, both machines dispense cash. The Lamassu requires a cell number to receive a code number text to sell. This is not required to buy.

The General Bytes machine does not require a phone. It simply prints you a QR code to receive the coins you send and after one confirmation you scan the same QR code and it starts spitting out banknotes. Fast, simple, elegant and anonymous.

I don't know about London. UK or ON?   Look here:

https://coinatmradar.com/