UTF-8, two languages, and Google

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I have a translation site (http://www.translationhelp.com) which has menus in English and content in various languages as determined by the translators who create the pages when they register according to their "target" and "source" languages. Eventually I will have the menus in the same language as the content, but that will take time and money.

My goal is to get these pages onto the search results pages of Google's many language/country specific search engines (Google.jp, Google.za etc.)
(Please excuse my ignorance on this topic. I am not a programmer and I cannot find the answers to these questions.)

My questions are:
1) Previously, the language charset in the meta tags defined the language of the page and Google could use that as its guide to where to put that page in the search results. When using UTF-8, how does the browser and therefore Google know what language the page is for if there are two languages on the same page?
2) Will having TWO languages on the same page preclude inclusion of that page in the search results for a specific language (the language of the content area of the page)?

I would appreciate any and all feedback on these questions. Thank you for your time and this great resource.