Hi Margaret. Here's the Guide on rich snippets for products: https://support.google.com/webmasters/answer/146750 What you'll be interested in making sure price and priceCurrency are correctly used. The snippet "priceCurrency" is, "The currency used to describe the product price, in three-letter ISO format."  Cheers!

This post is fairly extensive in regards to your question and should give you ideas even beyond what you're asking here,  http://moz.com/blog/hosting-and-embedding-for-video-seo but if you're looking for the highlight, this is still pretty applicable advice today:

Embed the content with HTML5 and JavaScript or Flash, but not an iframe

Unfortunately, Google are not very good at crawling iframes at the moment; so if you want videos to be indexed, you need to make sure you’re embedding content in an HTML5 player with Flash fallback, or a pure Flash player.

If the video is being embedded on your own site you can also create a transcription for it on the same page and then place the links in according spots.  Cheers!

Or make the Keurig sessions min-value:10 every day until this is solved.

Hi Prunarevic.  Can you clarify your question?  I'm a bit confused about what you're asking. Typical parasite hosting is accomplished by hacking into a website or finding an openly editable portion of a website and adding content that redirects to your target page.  It's not advisable, and if you break laws while hacking into someone's website it could be far more trouble than it'd ever be worth.

Kate Morris wrote a nice post on how to break up sitemaps for large sites a few years ago, but it still holds true today: http://moz.com/blog/multiple-xml-sitemaps-increased-indexation-and-traffic, so following the advice there should help on your first question.

Your 301 redirect to English should probably be a 302 and based on browser language settings.  Is it possible for anyone to get to a file or folder at www.example.com/whatever...?

Third, see the blog mentioned above. She gets into the details of how to create an Index format for your soon to be many sitemaps.  Cheers!

Per Google's recommendations here: https://support.google.com/webmasters/answer/2620865?hl=en, yes you want to have pages correctly tagged with their alternate language translations. Per the blog I cited earlier, you'll want to organize the sitemaps to break out the 200.000 pages in a structure that's more refined than just 'all', specifically in ways that will help you find if there are problems creeping up in one section or another. Good luck!

Mostly no on iFrames, or not in a reliable way. Redirect 303 is more uncommon, but similar to a 302. Either one is not the way to permanently send old content to new. Google has a guide on redirection here: https://support.google.com/webmasters/answer/93633, and iFrames here: https://support.google.com/webmasters/answer/34445.  Cheers!