Fields missing from CSV import

Hello,

Using ProfileGrid and RegistrationMagic together on my site.

My goal is to import a CSV format user list that is a purchased mailing list.

I experimented with the CSV export/import (ProfileGrid > Tools).

1. I exported my current user list of test records (no actual customers, yet).
2. Edited the list by adding one new entry, then imported the changed list.
3. The new entry appeared in the WP users and also a ProfileGrid profile. But it did not pick up the first and last name of the new user.

Question 1: What would prevent the new user first/last names in this CSV from being added?

Question 2: What controls which columns of user data are stored in the WP user database? Does this come from the RegistrationMagic form?

Question 3: If I use an imported list from elsewhere, how do I map the columns to match the fields in the user database?

Thanks in advance for your insights!

The page I need help with: [log in to see the link]