I seem to remember others have posted that they managed to get replacements in local auto-parts stores, but I just ran around for a few days with the flashing fast with no issues.
Which I guess answers your second question to some extent, but logically the only thing that could get damaged is the flasher which you are replacing anyway.

Caspian Blue '03 BA, Union Jack/Stars and Stripes paint, BUBs, Progressive 812s, and lots of chrome