How to deploy Language Packs to Windows 7 Enterprise domain clients using WSUS

This is a User config, you needed to have this apply to your environment based on the computer, not the user, so you'll need to set the Group Policy loopback processing. That is found under:

Computer Configuration > Administrative Templates > System > Group Policy > User Group Policy Loopback Processing Mode 

To set the policy for language and regional settings. In the console tree under User Configuration > Preferences > Control Panel Settings. Right-click the Regional Options > New > Regional Options

http://technet.microsoft.com/en-us/library/cc754020.aspx

To answer your second question about enforcing. I would create an OU for your Kiosk workstations. Under that I would create an OU for each Region. I would put each of your workstations in the specific region container. That way you can apply group policy settings to your Kiosk OU and it will apply to the Region OU as well. Then you can manage each of the regional options inside your Region OU

Kiosk
   |-Italy
   |-Russia
   |-Spain
   |-USA

There are two types of language packs.

One is the 100% translation pack, these require specific licenses. I believe a Volume License, with the restriction that the language you are trying to install is not priced higher than the language you bought.

Then there are the Language Interface Pack (LIP). The LIP contains only a subset of resources required for a specific language, no license is required.

Understanding Multilingual Deployments