Extraction Questions

Hi Gurus

Few simple but very confusing questions I need to get answers from you experts to make my base clear.

1. We have already set SAP BW system extracting data from SAP R/3. Now we have to add few fields to one of the cube ( 0PUR_C01) so pl tell me what changes I have to do as far as Job control in LBWE is concern? And where I need to do those changes in DEV or in PROD system?

2. Where can we use LBWE ES maintenance and when can we use coding in SE37 ? I think we use both to add some extra field in our extractors but not sure in which case we use what?

( consider the extractor is FM,Database view ot table)

Thanks a lot in adavance