Unfortunately it is even worse than that. The payment terminals automatically convert the received bitcoin to fiat CHF, which is booked some days later to the merchant's bank account.
Yes and no! They can HODL if they choose to. I couldn't find any that did though :/
  1. Bitfinex PoS
  2. Some use the Luga app which is actually quite good because of the cashback benefits. It's only available to residents. But probably Wallet of Satoshi as that one is most used by the world.
  3. That's quite loaded 🤣 They can HODL but they're not gonna hodl something they don't understand. They might start accepting bitcoin; learn about it then switch to HOLD mode. Equally, they might just forever convert to fiat. The choice is there and the reliability + education is fortunately on hand.