How to create a newsletter subscription form using Uniform & Mailchimp?

Sure, if you don’t need modifiable information (like a target email adress or an API key) for the form, a route is probably the better choice. Here you can find a neat solution using a route as endpoint for an AJAX form (not using Uniform though, but it works the same).

Yes but you don’t mean to copy the logic of the wrapper, do you? You only have to install it according to the readme and use the wrapper in the action. This way you can easily update it in the future.