Hi Christina Noel,
Indeed, if you want to update the localization in runtime, you need to reload the corresponding visual elements. Please take a look at our demos for a reference - each time you select one of the RadioButtons on the right, the language is changed. Basically, the idea behind is that the UI elements are recreated on updating the language.
Considering your second question, there should be no problem to localize a particular string. You can run through our online documentation for additional information.
the Telerik team
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