Check here for general info on HDTV in Canada
http://www.digitalhome.ca/forum
Quick answers to your questions:
-you need an HD terminal. Approx $10/mth to rent or $250 to buy ($550 for the HD PVR version). Sometimes the TV purchase will come with the first 12 months terminal rental for free.
-$3 monthly digital services fee , if you're not already paying it
-16 HD channels are free. There's enough HD content there to make it worthwhile, including all NFL games and most NHL games. There is an extended HD package for $7.95/mth that includes TSN, Discovery, A&E, HD Net. The extended package is usually included with the free 12 month terminal package if you get it.
-Most of your content from torrents is probably not HD. The true HD files are huge files (ts files?). I haven't tried recently but I think you'll need a special software player (VLC media player), a video card that can handle HD, DVI/HDMI connection from your PC to the TV. Check the forum above to research it further.
-HDTV free by antenna works but it's limited in channel content.
I notice that the 40" Sony LCD for $1799 at Future Shop, includes the Bluray player. Very good deal.