The odds are important to know because if someone gave you a trick coin that always lands on heads, you will be flipping coins until the end of the universe. And I'm sure you have more important things to do than that.
Nah, you can put in a rule to stop. It would be better to know ahead of time, but you don't need to.
> you will be flipping coins until the end of the universe
Reminds me of one of my favorite movies, Rosencrantz & Guildenstern Are Dead, which opens with just such a scenario[1].
[1]: https://www.youtube.com/watch?v=RjOqaD5tWB0