I wasn't sure how to do this either until searching some older posts on MR
- Add a new custom column (of type Text, or Comma separated Text if your books might be in multiple series), e.g. with lookup value "series_nic" and column heading "Series Nic"
- Restart calibre to show the new column
- Highlight all the books you want (I suggest you test on just 5 or so the first time)
- Click Edit Metadata (to edit all the books at once in bulk)
- Select the Search and Replace tab
- Change the Search Mode to "Regular Expression" (to the right of Search Field)
- Change Search Field to "series"
- Change the Destination Field to "#series_nic"
- Click OK
You don't need to enter any text to search for or to replace - it will copy the field by default. If it looks ok, run it on all your books.
You also asked about series number. Since this column will be used for collection names you really don't want a series number in them as it wouldn't make any sense since you would end up with 1 collection name per book.