V3 update and open hub questions

Hai There,

I have two basic questions.

1. In LO extraction we delete contents of setup tables before delta initialization and settingup V3 update. Once the setup is made and extraction is running, how many times do we delete the contents in setup tables? Is it every time the data is sent to BW delta queue or only once?

2. Why do we need openhub to transer data from once BW system to another BW system? We can do it with RFC also can we? I know that we need open hub functionality to transfer data outof BW system to other systems as it needs additional licensing. What about BW-BW system interaction?

I would appreciate any help and correction in my above statements.

Thanks.