Where can I store additional pilot information?

Answer:

Additional user fields (number and text fields) can be set up by a SYSOP in the 'User/Res Options' screen (Admin >> System Admin >>User/Res Options) seen below. You can also designate whether or not a user will have access to edit these fields.  If you want pre-defined options, enter the options by clicking on 'Edit Options' for the specific field.  Additional date fields can be set up by a SYSOP in the 'User Date Limits' screen within the 'Group Info' menu.

These additional fields will be displayed on the Status page of the user profile along with the user-defined date fields (e.g. Medical and BFR).

See below for example option box.