Karin:
That model is their Classic I think. It certainly would do just fine. My model seems to me to be a bit heavier, but they look almost identical - my poles are just a bit more robust than the Costco version.
That is a very good price. I would say go for it!
The top is attached with velcro. I leave mine on all the time. The walls are removable and are separated from the whole when stored.
I would get some white plastic 3 gallon jugs for weights. You can get some tension straps with hooks on both ends that tighten. You attach one end to the handle on the water jug and the other on the corner frame top of the canopy and cinch it down. With two of those attached, nothing short of a hurricane will move the shelter.