I heard that it will improve dynamic font support on mobile, is that true?
not that i know of.
Not too sure bout that. But you can just read it here yourself. The list of features going to be released. Unity Blog
And there’s no known date of release. But i am guessing July perhaps.
AFAIK 3.4 isn’t touching the GUI at all really (aside from minor bug fixes maybe) - the new GUI functionality is currently slated for 3.5. It’s probably a safe bet that new methods for displaying fonts will come with the new GUI.