The urge to cash out 5-6 hundred then sit in the bank for an hour or three before re-depositing the money back into the account would be overwhelming.
Eh. Drop it off at the nearest lost-and-found. If there is a number to the bank, I'd call it and let them know that person X misplaced their chequebook and to send them another. And ask the bank to scold them. Even if I drop it off, I cannot guarantee that it'd be safe, so having the bank void the numbers of the cheques might be optimal. Guilt really racks up stress, so not worth stealing from a careless person.
Depends, I would check whether it was legal in my country first. If it was, I would just cash it in. Guilty conscience be damned, its free money, I can deal with a shitty conscience if I get free money. I'm pretty sure that you can cancel a cheque though, so I would be careful not to draw out too much from the cheque, so the hassle of cancelling would take more effort than the monetary value gained from the cheque.
I.. probably wouldn't use it. I'd let @Arcturus use it to treat me to lunch, though. I have no qualms with friends doing bad things, even if I benefit.
Why would the bank use it for themselves.. For one, it's already their own money. For two, they rely on trust to function. If no one trusts the bank, no one gives the bank any money. They have to act responsibly and reliably. It's just business.
it depends on the context. I would like to believe wouldn't use it, but depending the time and place I might.
Banks don't trust their own employees, usually they have a ton of cameras at their local branch. Only management gets a level of trust.