Hello there!
Just to help Tawny clarify this.

In those reports, " Root Domain" means just the domain. In the case of Moz, it is a-moz.groupbuyseo.org. This also means that they are taking into account the whole site.
So, for example, consider that you have 3 pages:

1. site.com
2. site.com/landing-page-A
3. site.com/important-keyword

On one hand, if every page has one separate link pointing, fron different sites. Let's say: example-1.com, my-blog.org and site-overseas.com
In the report, when checking for site.com, you'll fine 3 root domain links.
On the other hand, if every page ( just to keep it generalistic, but it could be applied for just onepage) gets a link from the same root domain, but from diffetent pages (let's say: site-A.net/page1, site-A.net/keyword-two and site-A/whatever) in the repport you'll see just **ONE **root domain link.

Can you see the difference?

Hope I've helped.
GR.

Hi Raymond,

Keep in mind that you want to optimize a certain page for just one o two keywords. So with that idea, you shouldn't worry about the main keyword.
Im assuming that you're talking about you home page. For specific keywords, is advisable to have separate pages, a sort of landing page focused for that page.

Here some resources:

Begginer's guide - 5th chapter - Kw optimization
A Visual Guide to Keyword Targeting and On-Page SEO - Moz Blog
How to Optimize for Keywords in 2015 - SEW
On-Page Optimization for Keywords - Moz.com Academy

Hope I've helped.
Best luck.
GR.

Rosemary, please tell us how well this method works. It's hard, nowadays to rely on free platforms.

Hello Rosemary,
Yeap, it is possible to tell Google your sitemap. In this article (official Webmasters Central), they offer 3 options:

1. Via Search Console.
2. Via the robots.txt file.
3. Using a HTTP Ping.

Hope I've helped.
Best luck.
GR.

Hi there,

Yeap, subdomains are different sites to google from the root domain.

What you are willing to do is to non index the root domain.
Of course one way is to make a 301 redirect, if you still want to preserve the root domain visible I'd do these steps:
1. Set canonical tag in the home to the sudomain
2. Set meta robots tag to noindex in the root domain
3. Update the sitemap, leaving only what you want in the root domain. Update in SC.
4. Create a SC profile for the subdomain, create a sitemap and upload it to SC.
5. Wait

Hope I've helped.
Best luck.
GR.

Hi there!

tldr; Yes educational and governmental links are the same as any other link.

SEO has lot of myth, some came out of truth (because it worked some long ago) and some came out of the conspirational mind of tome people (sometimes triggered just to create engaging content).

My personal experiments, tells that educational and governmental links do not carry more "juice" than any other backlinks. 
I found that many people speak about those links as TOO VALUABLE because they are extremely hard to get. Guess what? Any extremely valuable link is also really hard to get.

I advise everyone that come across this topic, to focus their efforts in making the site great, not in finding impossible links that "promise" great result.

Hope I've cleared your doubts.
Best luck.
GR.