JSONP questions

  A few developers are working on River of News readers with the JSON river my news app is producing.
  There have been a bunch of requests that I support JSONP, which I am looking into.
  I understand that JSONP is needed so you can access data on domains other than the one from which the page originates. I also understand how it works in a simple case where a small amount of JSON is being returned. But I'm returning 70K of JSON text and it includes tabs, carriage returns and linefeeds.
  1. So the first question is -- should I strip out the whitespace characters?
  2. Are there any characters that need to be escaped or neutered? In XML you'd be fine if you encoded left-angle-brackets.
  3. What's the Content-Type? I'm using application/x-javascript for now. Is this correct?
  I'm sure there are other questions. :-)
  Update: There is now a JSONP version of the river.