I guess in practice you'd want to have Rust installed as part of your local build and test environment. But I don't think you have to learn Rust any more (or any less) than you have to learn Perl or how the config script works.

As long as you can detect if/when you break it, you can then either quickly pick up enough to get by (if it's trivial), or you ask around.

Depends on the change being made.

If they completely replace an API then sure, probably.

But for most changes, like adding a param to a function or a struct, they basically have to learn nothing.

Rust isn't unlike C either. You can write a lot of it in a pretty C like fashion.

That's exactly the original question.