[neverminder]

Regarding 5: yes there is, it's called Play Framework.

[goldbrick]

Play probably is the JVM world's best answer to Rails/Django, but it's neither as complete nor as frictionless. Source: I use both Rails and Play at my day job.

[talles]

But Play is sorta of a response to Django/Rails/Sinatra-like that came before, right?

Maybe there's a legacy effect here.

[davelnewton]

Sure, but that doesn't mean it doesn't exist.

There are several pretty light-weight ways to make both action- and API-oriented back ends on the JVM now, even in Java. (Although I prefer different JVM languages.)