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Most blog platforms offer the ability to not index various conglomeration pages (category, author etc.) I would recommend using those options so only the actual article page gets indexed.

I worked on a similar problem, we created an interstitial page for a general product and then used canonical tags to point all of the e-commerce product pages back to the interstitial page.

Ideally you would want one page where you could just select different options, but depending on your technology that may not be possible.

The first question is why are you going to have many stores doing the same thing, is each one unique in some way? 
Without more information as to why you are doing it this way it is hard to help with the best way to handle it.

No, not provided is only part of organic traffic that does not pass a keyword.  Any referral traffic you are getting will be shown in the referral section. There are a lot of reasons why what a site reports they sent and what GA sees are different, you should never expect them to line up, but with the difference that you are seeing you should check your GA installation to make sure it is done properly then ask what the other site considers a "click" as many automated functions like spiders will mimic a click, but GA does not track them as they are not people.

I have seen something like this before, it was a code error on the site, but they can be extremely hard to track down, if you can locate the page that these unknown page views are being seen at it will narrow down your search.

Some CMS would do that automatically, if the company you are working with had one of those (or the decision maker is used to seeing that) they may just think that it is normal and a best practice. At the end of the day, while odd now, it should not matter from an SEO perspective (just make sure that you redirect the base url to that page).

Why would you worry about SEO on pages that targeted? The only people you want finding them are the specific companies, I would no index all of them and use the best versions of the copy to create a few general landing pages.

Can you post a screen shot showing this.

If what you are saying is true, the issue could be from spam traffic spoofing your GA account number or from an improper install on your site (caused by things like iframes or poorly coded scripts).

The function of the meta description is to provide a snippet for the search engine to display, it is not a form of masking, that site is using the meta description for its intended purpose.

http://www.wordstream.com/meta-description

I think you are asking a large, loaded question.  I do not think there is a "yes you should" or "no you should not" answer for your complex question.

This content is upwards of nearly half a decade old, is it still relevant?  Instead of a blanket yes or no, I think you should go through all of it and see what is still valuable, depending on your industry it could be half of it, or it could be none, but you should be looking at each piece individually, not the entire site as one whole. For moving it, if the content is good I think placing it on your site (as I assume you want to consolidate) and redirecting to the new location is fine, plus if you do it as you go, you will not have a massive surge in your content, or drop in the old site but a gradual shift over a period of time.

Hope this helps.

So you are asking on Moz if you should steal content from Moz then not credit them to increase your search ranking, and then your concern is not if what you are doing is wrong (it is) but only if Google will penalize you for it?  I believe that if you want content for your site you should make it or pay for it, not steal it, if you write optimized content then maybe people would expect copy on your site to be written by you.

Write as much copy as you need to convey the information that is needed for your visitor on that page.  If you can create a good user experience on one page with 100 words (by answering the pain that they would be going to that page to solve) and then you need 1,000 words for your next page, then do that to.  Don't make arbitrary copy limits or goals based on SEO, make your pages user friendly and your copy useful and your pages will rank well for the appropriate content.

Unfortunately, you cannot from Google traffic. Ever since Google stopped giving search terms for secure searches (any time a person is logged into any Google property) directly linking keywords to performance has gone away.  The closest you can do is link landing pages to conversions and then see what keywords are driving to those pages.  While it is not perfect, it works well enough to make marketing and keyword decisions.

While they as a whole have high page authority, when you create a sub domain blog on them, it does not get the same.  You should worry about creating good content on your site instead of making free blogs to put content onto to then push to your site.  Your best bet would be to set up a blog onto your website so that you can have new, relevant content being consistently added to your site.

You are moving the wrong way, Google has said that they prefer sites to be secure and that this will be a factor more and more.  As per your question, yes if you create 301 redirects your SEO losses will be minimal (and don't forget to update your GWMT).

Yes all of those can negatively effect your ranking.

Look at your press releases how you look at content, if your press release is worth while and either ads value or answers a question then it can be useful as it will be picked up by relevant sites and used properly.  If you are just putting out press releases across sites which are spammy, then as Ryan said, they will not be helpful, or even have a negative effect.

Yes, it will show you leaving your purchase funnel at whichever page you viewed last, it will also show this if you are in your conversion funnel and you go back to other pages on your site and then leave.

A missing title is your meta title, it is the words you see in the tabs on your browser.

H1 elements are in your copy, each page should have one, and it should be the main focus of the page.

That is pretty odd that you are not getting traffic from Bing and Yahoo, as general SEO work for Google should also effect other search engines.  The first thing you should do is make sure that your site has been submitted to both and they have the location of your sitemap and robots.