It's pretty simple. Wordpress already has the concept of authors, with each author having their own bio page (www.domain.com/author/name).

So to add authorship, in your posts, make sure that the author's name in their byline is a link linking to their bio page, using the rel="author" markup. Many themes already do this automatically, but if not edit your posts.php and add it in.

Then, on the bio page just add a link to the author's Google+ profile using rel="me". That's it.

I don't think it makes sense to have star ratings on a testimonials page, the reviews should appear on the page about the product of service being reviewed, so all the reviews about Lawn Care should appear on your page about Lawn Care.

In general, what Google is looking for is reviews of your product that people have left on your site. Taking reviews from other sites and placing them on your site could be considered duplicate content (although Google themselves do this, go figure).

The semantic markup code you wrote above looks fine, just be sure to put a space where you put "itemscopeitemtype" (it should be "itemscope itemtype") and it should work properly.

I believe Matt Cutts once said that the backlinks in GWT are updated every 3 months or so. I'm not sure if the frequency has been changed since then. I don't know how often OSE updates.

It's best to keep track of your own backlinks. As long as the page that the link is on has been indexed by Google, then it is likely already being taken into account from the algorithm's perspective.

There is no set amount of outbound links that are the "right" amount. Just use common sense and don't be spammy about it.

Linking to other sites does pass some link value to their sites, so make sure that they are high quality sites. Linking to low quality sites can get you penalized. On the flip side, linking to high authority sites is believed to give your site a slight boost.