We only have the wifi router the landlord gave us and it drops a few times a day. Will a cloud based point of sale cope with that?

Yes, because the sale is written on the device first and sent to us second. When the wifi drops the cashier keeps selling, the change is worked out on the device, and a green line says the sale is safe and will reach us when the connection is back. The printer and the cash drawer are on your own counter, so both keep working. Everything goes up on its own the moment the wifi returns, and a sale is never sent twice. The one habit to teach: do not switch a device off while its settings screen says sales are still waiting to go up. The POS and the counter tab in the docs has a section on working with no internet.