Import/Export will include content as well. Mirroring is basically the same as automated export/import.

Regarding your question about import/export and templates the answer is no.

The templates are still physical files on your harddrive. The only thing exported are paths to your .aspx-file if you're using WebForms or what Controller is responsible for this Page Type if you're using MVC.

Is it a one time only-copy you want to do or something that is run to keep a sync?

Thanks - My goal is to export content (as in pages) and the associated files. (images etc)

It would be an initial one time only copy - to promote the site to production, then the staging server would be used to manage changes (with the copy happening nightly).

If I set up mirroring, can the services be hosted under SSL, while the site is normal http?

The most common way I've seen is to backup and restore the database and VPP files from your test/stage server to your live server.

And when you want to backstage (copy from live to test, stage and development you do the same but the other direction.

Given that you can replace everything and don't have content you want to save.

Edit

Sorry I think I missunderstood your intent with the environments.

I don't have that much experience with mirroring and if it's a good idea to use it for that purpose.