I have a few medium/large news sites in English and German. Sites are established with good traffic, tens of thousands of organic links etc.
We are about to launch some more in-depth topic sites that will act as sort of sister sites.
So say on the news site we have a page called Baghdad, that acts much like a tag page on a blog, except we can addattributes etc. Any relevant story we run on the news site links to that page and it just lists the stories.
On the topic site we will have more information on that so a description and other assets we don't carry on the news site.
I was going to link each tag type page on the news site to the equivalent topic page. Figured handy for users and good for seo. I was not going to recipricate the link as the topic page might well carry news story headlines from the news site.
I was also thinking on doing some text linking from actual articles, making it obvious with a little icon that an external link for further info. So a mention of Baghdad would go not to the news site's Bagdad tag page but to the topic site.
We also usually have our main sites in the footer on every page.
Should I do all three or are some harmful in terms of search? I have no hesitation from a user point of view but I don't want to do any harm to the news site.
Also does the fact the sites are owned by us devalue the links?