Do automatic style hints help students to understand the language they're learning?
In my experience, immediate feedback is helpful in speeding along development, but rarely enhances understanding.  In fact, I am often frustrated with the immense level of help that is provided to my strugglers, because they wind up moving words around until whatever they've written stops being underlined.

The only exception to this has been for norms that don't cause errors, such as using CAPS for static final variables in Java.  In those instances, it is very helpful to have some sort of indicator that what they've done isn't perfect.

Edit: Now that I've seen your edit with examples, it seems like what you are contemplating is basically all of the stuff that I feel is helpful.  In which case, I believe that it could be very helpful!