1. The removed values will remain in the instantiated objects' attributes. If an object is edited, then the old value will no longer be available. 2. No. Once you use a manuually defined fixed list, you cannot switch between that and a db lookup. To use the same attribute name, you would have to delete the attribute values from all of the objects, delete them from the attribute definition, then enter your query. Alternatively, you could rename the old manually defined list attribute, remove it from the object classes and add a new attribute with the name you want.
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