Yes to both of your questions. People say those things.
Strictly speaking, choices and options are different things, but in normal spoken and written English, they're usually considered interchangeable. Only peevish pedants would dispute that, except where stipulated that they're different.
You can replace "legs" with "shank's mare".
I don't think I'd say "Legs are a choice I could use to get to work instead of using the choice of a car". It's verbose and a bit awkward. I'd probably write "Legs, instead of a car, are an option for getting to work".