I have read the United TravelBank wikipost but have not completely comprehend the contents, so if someone could answer my belew questions, I would greatly appreciate it.

1. I am under the impression that if I use travelbank cash to book a UA flight and cancel AFTER 24 hours, I'll be getting a travel credit (in lieu of money refund back to TravelBank) which I have to start travelling before 12/31/2022. Is this correct?
2. Is UA travel credit and travel certificate the same? To me, travel credit is the credit I get after a ticket refund, and it is a 6 Letter/Number reservation confirmation code.
3. I read it somewhere that up to 10 UA travel certificates could be used for a single flight booking. Does this mean 10 travel credits, or up to 10 previould cancelled flight credit could be used to book a new single UA flight?

Thanks in advance for your help.