Design Process chain for automatic Data Update

Hi every one,

i am watching Video about creating Process Chain.

According to this Video: RSPC Process Chain BW - YouTube   (minute 8:03)

the created Process Chain in Video is:

Start -> Delete PSA Request (Delete PSA Service Level) -> Data Target Content (Delete Cube Service Level)

-> Load Data (Info Package Service Level)-> Data Transder Proc.

so i want to ask some questions:

1. Why we need the Process Variants: Delete PSA Request (Delete PSA Service Level) -> Data Target Content (Delete Cube Service Level) ?

because  i have watched also some other Videos, the Process Chain was designed very simple, like this: Start-> Loas data->Data Transfer Proc

2. Incase if i load a Standard data Source from R3 to BW, and i need my Data to be automatic updated daily, which Process Chain should i follow

Thanks