Hi Diane,
There is no threat of data loss while deleting the set up table.
Could you please let us know the datasource which you will be using or the application ?
To answer your 2nd question data can be fiiled in the set up table based on the fields which are available there.
If there is no calyear/calyear/month field you need to check the source tables for the data according to the field availble and then fill accordingly.
Hope this helps.
Regards,
Amit