Hi Marek Konecki,
I put some short answers to your qestions to pinpoint where you need more information:
1. We have a VSchema tool that allows database schema operations - we use it for our forward-mapping capabilities. In design time if we have sufficient information about the schema we are able to recreate it from our model in the database.
Additional to that we have generic data access API that allows runtime schema modifications. Currently we have field/column modification in place (CUD operations). And with our next release we will have also class/table CUD capabilities.
Schema migration is not supported out of the box currently.
2. We have support for structures, you have to find whether it works for you. The structure fields are flattened down to the same table where the parent class resides. Because structures are valuye types we cannot detect automatically updates there (because they are done on the copy) and that requires additional operation, like assigning the structure back to the property it is exposed from.
3. We support polymorphic queries (I think that implementing an interface is similar). I am absolutely sure about OQL, I will have to double-check for LINQ though.
Please do not hesitate to ask additional questions that you might have.
the Telerik team