hi abhi,
i didnt search on CIC or CHC website but i collected some information from this forum and GCMS notes.
after file transfer to VO, they can request passport any time before your visa is ready to issue, in ND, they request passport at first and hold your passport for whole time, if you dont send at first and ask them to request your pp later, they will request at the end.
after assigning file no. and visa officer, initial review is first step, conducted for eligibility test. if they are convinced with your relationship with sponsor and your intention after immigrating to Canada, they send your information for background and security checks and update your ECAS to "in process". if they have doubts about eligibility, they request additional docs or interview and after successful interview, go for BC and SC. after receiving your report from security agencies, they do final review and issue visa.
after completing each step, they assign one BFD (bring forward date) to your file and open your file again on that date.
hope it helps
