Hello Alexis,
Luckily, I/O Runtime is built on top of an open source project, Apache OpenWhisk. There are a ton more of resources out there that go in great details. I noted this request, and when time permits we will add a more detailed docs on creating RESTful APIs.
Regarding Cache Control, you can find an example here: https://www.adobe.io/apis/experienceplatform/runtime/docs.html#!adobedocs/adobeio-runtime/master/gui... Doing a redirect, would be as simple as the example above, just using the redirect header.
Cheers,
Mihai