questions regarding creation of vendor in different purchase organisation

Hi abap gurus .

i have few questions regarding data transfers .

1) while creating vendor , vendor is specific to company code and vendor can be present in different purchasing organisations within the same company code if the purchasing organisation is present at plant level .my client has vendor in different purchasing org. how the handle the above situatuion .

2) i had few error records while uploading MM01 , how to download error records , i was using lsmw with predefined programmes .

3) For few applications there are no predefined programmes , no i will have to chose either predefined BAPI or IDOCS . which is better to go with . i found that BAPI and IDOCS have same predefined structures , so what is the difference between both of them .