1. If a site is hosted on a UK server, will it appear higher in Google UK searches? 2. Does this <meta name="Language" content="en-us" /> effect where it appears on different country searches? I.e, if I change it to "en-en" will it appear higher on UK searches? Thanks.
I think I does not matter if you site is hosted in UK or somewhere else. Google will index your website and ranks your site depend on country, where someone is looking for something in that country.
Your ranking in Google searches will depend largely on your keywords and links pointing to your site but in terms of local searches, it does help that your site has a co.uk domain but if your competition has higher keyword density and more links, even if they're not hosted on a .co.uk domain, they would still rank higher than your site.
1. You would see better UK results using a *.co.uk extension, also don't forget to set your geo-targeting to the UK in Google Webmasters Central. Additional hosting your site with a UK hosting company will give more relevance to that region. 2. This is more used for validation purposes in browsers, it has never been "officially" confirmed or denied if this has any real SEO value. Many sites rank in top results without validating a language. For validation purposes you should use this meta element.
Remember the above 2 tips and don't forget to get some good backlinks from UK targeted websites ... Remember Quality Links