Thanks for your answer. Regarding the funding policy, that's what I have read as well. But I guess that there might be other policy for international PhD students. I've received an e-mail from my prospective advisor informing that I was admitted to the McMaster doctoral program but need to wait for funding decision, since the "funding is limited for international students" (perhaps this year). I'm currently in a decision phase and I have few schools whose deadline for final notification will expire in March.
As for the deferral, I wonder if you know the policy of the school. I tried to find this information in the PhD handbook but couldn't find it. Or any one who knows about this issue?