h1b stamping in India

Hi, my petition has been approved in July 2014 for 2015 cap. So visa will be approved from 1 st Oct 2014. I have couple of questions.

  1. Will it affect stamping if I delay interview date? If I go interview in 2015?
  2. What will happen if I get rejected in interview? Will I able to apply it again? If yes after what period and how?