This month's Dr Jobs on the University Affairs website is about getting jobs in Canada:
http://www.universityaffairs.ca/_careers/dr_jobs/index_e.php.
You can find out about the Canadian PR applications from the Citizenship and Immigration Canada website, which you may have already found since you've been looking at the points required for a skilled worker visa. The processing times are also posted and may give you pause for thought:
http://www.cic.gc.ca/english/department/times-int/02a-skilled-fed.html.
The other thing to remember is that, once you get a PR visa, there is a residency requirement (which I think is 2 years in 5, but I'm not sure). If you spent longer than that outside of Canada, you would lose the PR visa and need to re-apply if you wanted to go back.
As for the UK, it's definitely worth applying for jobs as an American. The main concern at the moment, as you will have read from other posts, is publications for the RAE. So if you've got good publications, you're halfway there already!
I second previous comments that this is in the wrong forum. You could PM the moderator and ask them to move it for you.