Thanks much Tanaka for the prompt response. There will be more doubts and queries which I will be posting in due course.Hi and welcome to the forum,
1) Yes you do. Tell them you need Upfront medicals done, so you will not have the IME number. Most physicians are stuck in the old system, so you have to insist.
2) IRCC will send you the letter after you submit your PR application.
http://www.cic.gc.ca/english/information/security/police-cert/asia-pacific/singapore.asp
All the best
Cheers
V