I can't answer all of the questions, but I can help you out with some of them:
1. Given that it's national newspaper, the PR of the site should be fairly high, and this should flow through to the article page. Building up the links to the article page seems like a lot of effort that could be better spent getting more quality links to your site, but i can see that this could have some benefit.
2. The article will certainly end up in the archive. it is unlikely, hwoever, that it will be deleted. Think of it from the newspapers perspective for a second. What benefit would it bring THEM to delete the article? None. These types of sites want great quality content that receives inbound links - deleting pages that could potentially have inbound links would be a terrible SEO strategy.
3. Only if it redirects and forwards properly (see next question)
4. Yes, but you will lose some of the link "juice"
5. I'm not sure on this one. I would like to think this an evolving process, but I don't have any facts to back this up.
6. Seems like it could be a lot of effort if you were to do this for every article you get published that links back to your site. You will only be boosting the PR of the site hsoting your article, only a small proportion of this will eventually get back to your site. You could spend this time and effort getting quality links to your site.
7. You will receive some link juice. You may find conversions are higher after people have read the news article.