|Possibly CurtR (I think he's in either Alberta or possibly Saskatchewan - both get quite a bit of the white stuff) may chip in too, as he is quite well up on the antenna approach.|
LOL I am presently living in northern Alberta (2nd time living in AB) but born and raised in Saskatchewan. I've also lived in Nova Scotia and BC over the years.
If you have the $$$, then definitely bury a conduit and pull cable. I can't think of the name of the grade of conduit but it's grey, flexible and the least expensive you can find. As to which cable (5e or 6) I'd go with whichever is less expensive as either will do the job quite nicely. Also, whichever cable you do buy, make sure it's outdoor grade. That has a much heavier casing and is usually packed with grease. This helps to prevent problems with moisture. It goes without saying, you want the conduit sealed tight.
Around here we bury conduit 6' (2m) or more because of frost in the ground. I'm not sure if that's an issue in PEI but find out what usual depth is for that kind of stuff. Also, get conduit that's big enough to hold 2 or 3 cables if possible. You never know when you may want another and you could also use one pair from one cable to extend your telephone out there if you so desire.
I won't matter which router you get so much. Just be sure it's dual band and can handle both 2.4 and 5.0 GHz. Also, ensure they run at the same time. Some of the cheaper SOHO routers can only have one radio running at a time. You want both and it won't cost much more.
I would suggest you go with the same brand as you have in your house if possible. You'll be more familiar with the interface and setup. Have a look at my how-to guide detailing 'adding a second router' (click on my name above and then click on my how-to guides) and pay attention to the scenario where you're going to be using the same subnet on both and connecting LAN port to LAN port on the two routers.
When I recommend point-to-point wireless antennas it's usually a case of saving some $$$, distance between points and/or convenience. They're pretty easy to setup if you buy the right ones and normally will do the job quite nicely. But if you can afford the time and money to bury a conduit. I would recommend going that route over p-t-p every time as it is more reliable and provides better performance.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.