Welcome to the Q&A Forum

First of all, good luck with your new website!  Now onto your questions:

1. I wouldn't suggest taking on every imaginable category of news, instead I would focus on one topic.
2. Your sitemap should only links to pages on your website, however the pages should (and most likely must) present the source of the original news article.
3. Yes.
4. For text a regular sitemap will work, for video check out video sitemaps, and I am not too sure about podcasts, maybe someone else will be able to chime in on that.

Resources:

Creating sitemaps: http://www.google.com/support/webmasters/bin/answer.py?answer=183668

Creating a video sitemap: http://www.google.com/support/webmasters/bin/answer.py?answer=80472

Very nice feedback, thanks for this.

I'll use the mac software omnigraffle to chart out my site.  Also someone came up with a cool applescript that will take a regular xml sitemap and turn it into omnigraffle.

Yes, in fact I have heard the new "caffeine" algorithm google uses favors social network links.   Even if the link is no-followed, the link juice will still flow.

Target good keywords!  For example, if I were selling golf clubs I wouldn't spend all my time optimizing for the term "Golf" or even "Golf Clubs" I would spend time going after keywords like "TX-90 Golf Club" or "Cheap golf clubs".

First of all, good luck with your new website!  Now onto your questions:

1. I wouldn't suggest taking on every imaginable category of news, instead I would focus on one topic.
2. Your sitemap should only links to pages on your website, however the pages should (and most likely must) present the source of the original news article.
3. Yes.
4. For text a regular sitemap will work, for video check out video sitemaps, and I am not too sure about podcasts, maybe someone else will be able to chime in on that.

Resources:

Creating sitemaps: http://www.google.com/support/webmasters/bin/answer.py?answer=183668

Creating a video sitemap: http://www.google.com/support/webmasters/bin/answer.py?answer=80472

I'll use the mac software omnigraffle to chart out my site.  Also someone came up with a cool applescript that will take a regular xml sitemap and turn it into omnigraffle.

Yes, in fact I have heard the new "caffeine" algorithm google uses favors social network links.   Even if the link is no-followed, the link juice will still flow.