Audacity will only run 32-bit effects on Windows.
If the message said that default settings will be used, that message should only occur once.
GSnap does not work properly in Audacity because Audacity does not support MIDI tuning. Here is an alternative: Autotalent for Windows (VST) http://www.vst4free.com/free_vst.php?plugin=Autotalent&id=842
. It might be better for your screen reader too, given it only has a text-based interface.
If you still prefer GSnap, navigate to the "Manage Presets and Options" button, choose "Options", uncheck the option for "Enable graphical interface" then restart the effect.
The best list for getting help is Audacity4Blind: http://wiki.audacityteam.org/wiki/Audacity_for_blind_users#docs