Is it too new to take on?
This is opinion-based, and thus off-topic
Apparently I have to have a separate website
You need a separate application (i.e. index.html + bundles). But you could serve all those applications from a single URL, deciding which one to serve on the server. That will (hopefully) change with Angular 7, when the new dynamic i18n, built on top of Ivy, is available.
is it a case that template files are dynamically inserted each time?
Not sure what you mean. The translations of the locale you build for are stored in the generated template classes at compile time, by the Angular AOT compiler.
Is there a way to do live language switching with angular i18n?
No, and that won’t be possible with the next version of i18n either. The same, unique application will be able to run in several languages, but the language will still have to be chosen at startup, and you’ll have to restart the app to choose another language.
Is there a way to do live language switching with angular i18n?
No. Not efficiently at least.
Is that what they call JIT?
No. The JIT compiler is what compiles your HTML templates into JavaScript at startup, in the browser. In production, you use the AOT compiler (which is also used to integrate the translations into the generated JS classes), which does a similar compilation of the templates, but at build time rather than runtime.