CRM extractor for BW

Hi,

Currently we are using cmod exit and function module to enchance CRM datasource to BW. I would like to know how to implement BADI and what are the different between MFLOW, SFLOW and BDOC. Most of the posting I am finding is regarding transaction data. Can I use BADI for master data as well. e.g (Relationship and BPartner)?

Regards,

Daisy