Basically, the answer is no to the file name. calibre will normalize the filename for the internal library copy. See
Want to change folder structure or file names in the Calibre library? as nothing has changed in that regard.
As for tags and other metadata? Unless you run Polish or ModifyEpub, the copy of the file in the calibre library will not be modified beyond what DeDRM needs to do. You can always save to disk a copy using either a template to rename or a simple rename after the copy without modifying the metadata (uncheck Update metadata in saved copies in Preferences => Saving books to disk).