Andrea,

You're OK using "postcard" in the child pages with child pages you mentioned, as those topics can be written about in ways that indicate distinct differences from the parent topic. However, in those pages, I'd limit the use of "direct" in your copy in order to distance them from the topic of the parent page.

As an early member of Moz, I can tell you that what brought me back to the site everyday was the blog and the comments on the blog. However I rarely commented on posts,  I didn't didn't answer or ask any Q&A, and I  didn't use the tools very much (although I used free tools at other sites pretty often) but I thought they provided a lot of credibility.  The content was very high quality and taught me to do my job better. You could tell that quite an investment was being made in the content and that there was a dedication to it and the community.

It's my feeling that it was the content and the tools that developed nurtured a community Q&A section--it didn't just spring out of nowhere.  A lot of work first went into building a community where a Q&A section could flourish. I think the long term rewards will be worth it as long as you're in it for sake of building a community and not for the sake of any SEO value the community can provide.

Well Howard, it's very true that there are many blackhat techniques that work.  The reason they're called blackhat is that they go against search engine guidelines and thus are risky, short-term strategies.  People aren't going to be arrested and thrown in jail for using them (typically) so everyone does have an opportunity to join in that fray.  If you're not up for techniques that may leave you high and dry when you wake up tomorrow morning, or that don't add long term value to a commercial domain, it may just be enough satisfaction for you to know that people employing techniques like those you're describing are often the ones screaming the loudest in forums about how they got scerwed by Google and how much money they lost when Google updates their algorithm.

Yes, if content on your site acquires new links, those links can help with the authority of your services pages as well, but it takes more than authority for those pages to rank.  On-page optimization for appropriate keywords is also important.

Yes, links to your homepage and your interior pages will help the authority of the other pages and, if they're optimized well, can help with their rankings as well. Good links to a page of a website does a positive effect on all other pages.

I am missing something here though--what is the purpose of your "core targeted page"?  "I'm wondering if 1-2 additional internal links from blog posts a month is really going to be enough?"

Enough for what?

It appears that your site hasn't been crawled by Moz yet and that it may be new.  It will take time and considerable effort to build your domain's authority. Be sure to read through The SEO Guide From Moz for info on how to increase authority.

Gavo,

It sounds like you might be going down the wrong path on your authority building. While the urge to do something concrete and countable like "link building" may be strong, you and your site will be better off if you resist. Spend time (and money if necessary) on figuring out how your site can "earn" links and then work to earn them.  The reason is that the kind of link building that you're asking about isn't worth your time, is not going to add value to your domain, and most importantly isn't going to add to your bottom line.

Are those other domains also yours, by any chance and/or is this a Joomla cms?