1 - Yes, you can. However, you should have in mind that the internal builds that we release are not as thoroughly tested as our official releases, so you should pay more attention when publishing app with these assemblies. As to the next release, it will be Q1 2013 SP1, expected in early April.
2 - I agree that the documentation is confusing. What we had in mind is that you have two options for using string loaders. The first one is setting the string loader to the InputLocalizationManager's string loaded and the second one is setting it to the global string loader. When using the second approach, you need to make sure that the assemblies that are expected to use the global string loader don't have their own string loaders and this can be achieved by setting their string loader to null. In short, first approach:
We are going to update the article in order to make it more clear.
the Telerik team
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