Firstly: Every column in the data file needs to be accounted for. If you don't want to load it to a table, just specify it as FILLER:
...
( NBR1 FILLER -- '123'
,data1 char -- 'G'
,NBR2 FILLER -- '100'
,data2 char -- 'data'
,NBR3 FILLER -- '122'
...
The rest of your questions need some before/after examples of what you are working with and what you expect in order to answer.