I am a US citizen, flying through Toronto to Edinburgh. I have a long (8 hr) layover and would like to leave the airport and go to downtown Toronto. My bags will be checked through to EDI. Would I need to collect them and go through Canadian Customs and Immigration to leave the airport or can they stay with the airline? Also, how long should I expect it to take to go through C&I? And how long to go through security on the way back in to the airport?