Replying from Simon Fraser University's perspective.
1. SFU's practice is to admit the best student who matches the faculty's interests, no matter where they come from. In many cases, the decision of who's "best" is based on the applicant's first-contact with a faculty member. (The practice of most of the faculty of science is to discourage applications which weren't sponsored by a faculty member, so that first-contact is incredibly important.)
2. There are loads of Americans teaching in Canada and at SFU. Getting an academic job is as easy here as anywhere else. Which is to say, it's tough here, too, but do-able if you're good. FWIW, there were 30'ish new junior faculty members at the faculty orientation this fall.
Americans actually have the easiest time of all our international grad students, in terms of getting across the border, because of all the free trade agreements.
SFU's tuition is also low compared to the US: $5k per year (based on 3 semesters), no international differential fee for research-based programs. If you TA, the basic health plan is part of your compensation, and the extended health plan (dental, vision) is $400/year through the grad student society.