Yes it is possible, in fact it is preferable, certainly in your example.

You would create a table for each of your "flat-text" files.

You can, but I would heartily recommend against it.

Yes...although database schema and design is beyond the scope of this reply at the moment (I'm running late for an appointment)...If no one has jumped in to assist further I can elaborate when I return - sorry :(

The simplest way for you to get started and get your feet wet so to speak is use the nph-setup.cgi file and your 3 different cfg files (make sure you check the format of the included cfg file with dbSQL - there is an added field for "Is field indexed"). Run nph-setup.cgi 3 times - before each time editing within nph-setup.cgi the hard-coded cfg file name to match each of your cfg file names. Look on line 55 of nph-setup.cgi.

2 most important things to do for now to get you started :

1. Make sure your cfg files match the format of the included db.cfg noting the extra field definition as mentioned above.
2. Edit nph-setup.cgi before each time you run it to reflect the cfg file name you are going to create a table for.

Hope that gets you started.

easy does it