enu stands for En glish U nited States.
in the keyboard settings you can select your languages. go to:
Settings -> Keyboard -> choose keyboard languages
you can deselect either English United States (ENU) or English United Kingdom (ENG)
You can change the Region and Language in your phone's settings.
You can also view the app store for another region online by going to http://www.windowsphone.com/[LOCALE]/store .
United States (EN-US) Store: www.windowsphone.com/en-us/store
Russia (RU-RU) Store: www.windowsphone.com/ru-ru/store
British (EN-GB) Store: www.windowsphone.com/...
On WindowsPhone.com, there is a pretty good tutorial on this.
1. On Start, flick left to the App list, then tap Settings > Keyboard.
2. Select all the languages you'd like to be able to use from your keyboard.
The next time you use your keyboard, you'll see a button next to the Space bar
that indicates which language you're currently using on ...
Cortana is available in China. But the language must be set to Chinese (simplified) or 中文 (简体). Bing translate indiactes that you have set the language to China (People's Republic of China) or 中国（中华人民共和国） which is not supported by Cortana. In case you want to know Chinese (simplified) is located next to China (People's Republic of China).
So go to Settings -...
A couple people have reported the same issue here: http://forums.wpcentral.com/windows-phone-7/177931-marketplace-wrong-language.html
If it was a mistake in the update, there is probably nothing you can do to fix it until a new update comes out.
I don't think you can change the language for speech (Microsoft Tellme) without the restart. I don't remember setting any setting in the phone specific to speech.
If you are a developer writing phone apps, you can change the settings in your app, thus allowing the owner to customize their experience, but that is per application.
I'm in the exact same position as you and to my knowledge it is not possible to change your Zune country. You can change your Live ID country but that doesn't affect the very important Zune country which is set in stone when you first select it.
Looking forward to Windows 8 where I assume my Zune account will become even more important I'm dismayed by the ...