For the first part of your question, yes, something was done and your DB was upgraded. Don’t worry about that ?? Although I’m not sure about the second…
Am I correct in assuming that your database is called e.l.m? I’ve done some trials and I can’t get mysql to accept databases with periods . in them anywhere. Try renaming your database to remove the periods and try again.
You should be able to go to domain.com/author/nick to see all posts by ‘nick’. Although I’ve heard mixed reports that the author/ URLs may be broken in 2.0.
It won’t be easy. Try changing the spreadsheet so it has the same columns as the wp_users table, then export as CSV and import that through phpmyadmin.