Sorry for the delayed reply. Some answers in short:
1. Yes you can pass XML dynamically which overrides the config file behavior.
2. You don't have currently a way to implement fetch groups dynamically. There is a default group for every persistent object which will load all the properties however.
3. You can do so by executing a scope.GetSQLQuery() and you should get persistent classes as a result.
4. We do not support third party cache layers at the moment.
All the best,
the Telerik team
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