Done

<a>http://en.wikipedia.org/wiki/Moz_(marketing_software)#See_also</a>

Many people don't realize that Keri Morgret is the demigod of content.  She goes by many names, but she is best known as Morgretra Goddess of Content and Gummy Bears.  Check Wikipedia if you don't believe me!

Please...dear God don't scrap your website (especially if you are ranking well for it).  Even if the content is completely different, figure out where to redirect your legacy pages to and use 301 redirects.  Just make sure that you are doing one to one redirects to maintain as much of your link equity as possible.  Sorry for such a short and simple response to your long question, but this only required a simple answer.  If you are offering the same products or services create a massive .htaccess file and redirect the hell out of your old site.

You owe me a Coke.

I only know what I do when I travel out of the country.  I always (without exception) go to Google.com instead of the country's version of Google that I'm visiting.  I'm positive that most everyone does as well.  It is just a little slice of home, just like reading English newspapers or visiting English Forums.  The only exception would be for local businesses, but that doesn't pertain to you anyways.  I would say that if you are ranking well for .co.uk that you should be fine if you are targeting ex-pats in Dubai.

Considering that (not provided) comprises 75% of my search queries, do you really think that Google will be transparent with this?

This is from Google:

Not all referrals from Google.com domains come through organic search or AdWords ad listings. Referrals may come from a variety of sources, including Google Groups posts, base.google.com listings, or static pages on related Google sites. Such visits are tagged as [referral] instead of [organic] or [cpc].

cited: https://support.google.com/analytics/answer/1011811?hl=en

I hope that helps!

I think that the better tactic would be to create new content for those broken links.  Unless these links are located on a very bad domain (link farm, etc.), I would just create a new page.

Be careful before you start messing with the disavow tool.  The only time I would use the disavow tool is if the link is obviously bad.  Like obviously obviously bad (if that makes sense).  Many people assume that their ranking tanked because of some algo update and start disavowing links without really checking into it.  Just be careful before using that tool and research the hell out of the link before you throw it away.

Here is a good article that gives you the Do's and Don't of using the Disavow tool.

http://www.portent.com/blog/seo/google-disavow-links-tool-best-practices.htm

Good luck!