importing / editing xls sheet--2

I am trying to input additional information to an imported xls sheet.

* I have added and changed single line fields on the imported sheet, but only the
first of these numerous changes appears in the Views section (This appears to
be a problem).

* despite adding fields to the imported xls sheet data, is it possible to later add
information in the new fields in the revised xls sheet?

* what then are my alternatives...?

Thanks.

ATP