Hey Mark! I think you can try modifying the Experiment Assignment Query in your Datasource to load rename the parameters this could work fine. At the end of the day so long as the query is pulling the right user, experiment, and variation IDs it should work with our system.
So I think your answer to 1 is no, since we pre-populate some queries based on your data source and yours wont' be what our query generators expect.
But I think your answer to 2 is yes, you'll just need to modify those queries.