Well apparently only 3.1% of the population has credit cards so probably they don't even have a card reader:
She used "wallet of satoshi" which is a banking payment app for Bitcoin based in Australia and not a self custodial wallet (I have several suggestions for self custodial lightning wallets if you're interested)
and yeah I can't answer what the fee charged was. It wasn't in the video but its usually less than what a credit card company would charge for sure (obviously exceptions exist for if you have a lightning channel partner with the worst person in the world, but you would have to be trying to make it bad)
I also can't answer how many cash vs Bitcoin payments they get, but its likely its mostly cash with the only exception to cash payments being Bitcoin.