The Walking Dead Episode 1: A New Day now costs absolutely nothing on XBLA and PSN. It's free worldwide on XBLA and just in North America on PSN.
There's no word on when The Walking Dead's second season begins, but when it does Telltale promises it will involve Clementine and Kenny in some fashion. The Walking Dead season one launched on Vita in August, complete with the 400 Days DLC. As far as add-on content goes, 400 Days is an extra-emotional festival of painful interpersonal interaction. Which is to say, we enjoyed it.