Welcome to the Q&A Forum

They may already know this.

It is my understanding that pinching someone's content and putting a canonical tag on it does little. if you were to put a canonical tag on your site pointing to theirs then that would be a signal that they are the original content owners.

having a page domain.com with a canonical tag pointing to domain.com does nothing,

having 2 pages domainB.com and domainA.com one with a canonical tag pointing to the other tells the search engine the other is the one to give credit to.
If you don't have access to the other sites, a canonical on your own site is not going to do you much good.

Unless those subdomains for single page sites, may look spammy to google. you can put those pages in your own site, there is nothing to gain using subdomains

I agree with Robert, one website, I would not worry.

Google is looking for a pattern of manipulation.

too many links with same link text is a bad thing, but google is smart enough to realize that one website is not manipulation

Your content needs to be in the html.

You can hide it with display:none and then show it via javascript, but it needs to be on the page.
I would not use such plug ins, I cant see them fixing the problem and will further complicate your site and crawling

WMT can take a long time for anything to update.

but the search engines would have that change by now in there index

Just

why do you have 3 websites with same content?

what are you trying to achieve?

Are they on different tlds, .for example .co.uk .com.au

Yes sounds strange.

Here is a tool that may interest you.
http://www.webworkshop.net/pagerank_calculator.php

Have you don't any link building recently or in the past?

How do you mean navigated by cookies?

I would backup your htaccess file.
then remove half the rules, then test. then you will know what half it is in. keep doing this to you find it

I don't know anything about xcart,but I know that some cms turn off htaccess, such as joomula, there may be a interface to turn it back on.

"everything your last post posited was incorrect."
so you say

"a lot has changed since this article was published in ---> 2007 <--- no-follows weren't even a figment of anyone's imagination back then, let alone a reality"

I wrote that article more recently then 2007, and yes no-follows were around, but are irrelevant, as I don't suggest using them and never have

""Rand and I both tend to believe that it is likely Google has changed and refined the PageRank algorithm many times."

Yes I agree, that's why I said
" test have shown that while google has changed many things, PageRank still works much the same as it did when Google published its algorithm long ago."
The whole idea of PageRank is the amassing of PageRank on pages due to linking as stated here in Wikipedia.
http://en.wikipedia.org/wiki/PageRank

I cant find the bit about spelling anymore, but I did find this
"Meta Keywords (fill them in if you like, keep it short and relevant, but not a big ranking factor)"

http://www.bing.com/blogs/site_blogs/b/webmaster/archive/2013/07/26/27-things-that-help-and-hurt-seo.aspx

Yes I think this is better then having thin content, your links if you are lucky enough to get them would amass on the same page.
You would probably only rank for the static content, at least over time, but that is probably what you want.
I would have access to this page via POST not GET to avoid querystring in the url

Because I have nothing wrong.
I have read the algorithm, I know how PageRank works, my explanation is the same as everyone else that has read it. including SEOMoz
http://moz.com/blog/how-pagerank-works-why-the-original-pr-formula-may-be-flawed

"If you're suggesting that no-following a link "keeps" more link equity on a page, you are incorrect. As I mentioned earlier to Kimberly:"

No I am not see my first reply.

"All followed links on a page pass link equity, and will reduce the link equity on the page the link is on."

all pages pass 85% of there link juice divided between the links on the page and keep 15%, no mater if you have one link or many.

Yes link position on the page does alter the link juice passed, but still 85% of pagerank still flows out though the links.

"how to PageSculpt navigational" links..." nobody does this any more, for so many good reasons. "

I would have to ask what those good reasons are?
internal linking is very important, test have shown that while google has changed many things, PageRank still works much the same as it did when Google published its algorithm long ago.
PageRank does amass on pages, there is no doubt about that.

If you no-index, any link pointing to that page will waste its link juice.
If you must do that no-index,follow so the link juice  can flow back out.
if your site is mainly duplicates then you have a problem, but if it is just a few pages, don't worry.
google will give credit to one page and will disregard the others.

As Andy said, you don't need to buy subdomains you need only set them up. but simply pointing a domain or subdomain to your site will not help.
Setting a separate website on the domain, can help, but only if that subdomain has links pointing to it, but then you would be better of getting the links to your primary domain. so I would not bother.

Bing uses Keywords I would keep them,

But don't try to spam them, I think Bing said something like they only use them if they are relevant to your content, adding different spelling and mis-spelt keywords was a recommendation

yes but that link juice circulates around the website and amasses on certain pages. the pages with the most links. What is important is that it ends upon the pages you want to rank.
http://thatsit.com.au/seo/tutorials/a-simple-explanation-of-pagerank