Travel request approval workflow
I am trying to configure a Travel Request Approval workflow scenario for my client. After a detailed analysis and a search through community, I understood that the standard travel request approval workflows are WS20000040 & WS20000050. But after reading all the stuff, I am confused and is having full of doubts. So I need your expert opinion to solve my following doubts:
1) If WS20000050 is for travel request approval, then what is the use of WS20000040?
2) Got an info from the community that, WS20000050 is triggered if we are using transaction PR04 for travel request creation and WS20000040 will be triggered if we use transaction TRIP. Is that true?
3) Whether these workflows are meant for portal use only or we can use the same in ECC side also? Because I need the approvel at ECC side only.
4) After an analysis, I understood that these are single level approval workflows. Is that true? Can we convert this to multi level workflows by some customizations?
Requesting all the experts to clarify my doubts with detailed explanations to each questions.