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You need to look at the bigger picture and not rely solely on Google Analytics, SEOMoz or any one tool in-particular. In the case of Google Analytics some users may not be tracked (not got JavaScript enabled) or you may be counting your own clicks on through your website if you don't exclude your IP address from Google Analytics. In regards to trusting SEOMoz with your Google analytics data, I think you can. As previously mentioned SEOMoz is a community of SEO's and the tools that SEOMoz provide can be enhanced by linking your accounts.

Yes. This is perfectly normal and common behaviour. In fact Matt Cutts confirms this in one of his videos on Webmaster Help channel on YouTube. Without knowing the exact technical details it's hard to know whether there is a risk for sure or not. The problem you have is the fact that Googlebot may not act as a geo user and you may end up with US or English language content only in index. Sitemaps or site structure will be a handy solution in that case.